diff --git a/src/cache/mod.rs b/src/cache/mod.rs
index c2c1ac9..ac8e0a7 100644
--- a/src/cache/mod.rs
+++ b/src/cache/mod.rs
@@ -168,7 +168,7 @@ impl<'data> ProguardCache<'data> {
             class: frame.class,
             method: frame.method,
             file,
-            line: frame.line,
+            line: Some(frame.line.unwrap_or(0)),
             parameters: frame.parameters,
             method_synthesized: false,
         }
@@ -389,9 +389,9 @@ impl<'data> ProguardCache<'data> {
         if prepared_frame.parameters.is_none() {
             for member in mapping_entries {
                 // Check if this member would produce a frame (line matching)
+                let pf_line = prepared_frame.line.unwrap_or(0);
                 if member.endline == 0
-                    || (prepared_frame.line >= member.startline as usize
-                        && prepared_frame.line <= member.endline as usize)
+                    || (pf_line >= member.startline as usize && pf_line <= member.endline as usize)
                 {
                     had_mappings = true;
                     rewrite_rules.extend(self.decode_rewrite_rules(member));
@@ -477,7 +477,7 @@ impl<'data> ProguardCache<'data> {
         'r: 'data,
     {
         if self.is_outline_frame(frame.class, frame.method) {
-            *carried_outline_pos = Some(frame.line);
+            *carried_outline_pos = Some(frame.line.unwrap_or(0));
             return None;
         }
 
@@ -678,11 +678,11 @@ impl<'data> ProguardCache<'data> {
             if let Some(mapped) = self.map_outline_position(
                 effective.class,
                 effective.method,
-                effective.line,
+                effective.line.unwrap_or(0),
                 pos,
                 effective.parameters,
             ) {
-                effective.line = mapped;
+                effective.line = Some(mapped);
             }
         }
 
@@ -903,7 +903,7 @@ impl<'r, 'data> RemappedFrameIter<'r, 'data> {
         let out = if frame.parameters.is_none() {
             // If we have no line number, treat it as unknown. If there are base (no-line) mappings
             // present, prefer those over line-mapped entries.
-            if frame.line == 0 {
+            if frame.line.unwrap_or(0) == 0 {
                 let selection = select_no_line_members(members.as_slice())?;
                 let mapped = match selection {
                     NoLineSelection::Single(member) => {
@@ -983,9 +983,10 @@ fn iterate_with_lines<'a>(
     outer_source_file: Option<&str>,
     has_line_info: bool,
 ) -> Option<StackFrame<'a>> {
+    let frame_line = frame.line.unwrap_or(0);
     for member in members {
         // If this method has line mappings, skip base (no-line) entries when we have a concrete line.
-        if has_line_info && frame.line > 0 && member.endline == 0 {
+        if has_line_info && frame_line > 0 && member.endline == 0 {
             continue;
         }
         // If the mapping entry has no line range, preserve the input line number (if any).
@@ -994,7 +995,7 @@ fn iterate_with_lines<'a>(
         }
         // skip any members which do not match our frames line
         if member.endline > 0
-            && (frame.line < member.startline as usize || frame.line > member.endline as usize)
+            && (frame_line < member.startline as usize || frame_line > member.endline as usize)
         {
             continue;
         }
@@ -1005,7 +1006,7 @@ fn iterate_with_lines<'a>(
         {
             member.original_startline as usize
         } else {
-            member.original_startline as usize + frame.line - member.startline as usize
+            member.original_startline as usize + frame_line - member.startline as usize
         };
 
         let class = cache
@@ -1035,7 +1036,7 @@ fn iterate_with_lines<'a>(
             class,
             method,
             file,
-            line,
+            line: Some(line),
             parameters: frame.parameters,
             method_synthesized: member.is_synthesized(),
         });
@@ -1105,12 +1106,12 @@ fn map_member_without_lines<'a>(
         class,
         method,
         file,
-        line: resolve_no_line_output_line(
-            frame.line,
+        line: Some(resolve_no_line_output_line(
+            frame.line.unwrap_or(0),
             original_startline,
             member.startline as usize,
             member.endline as usize,
-        ),
+        )),
         parameters: frame.parameters,
         method_synthesized: member.is_synthesized(),
     })
@@ -1142,12 +1143,12 @@ fn iterate_without_lines<'a>(
         class,
         method,
         file,
-        line: resolve_no_line_output_line(
-            frame.line,
+        line: Some(resolve_no_line_output_line(
+            frame.line.unwrap_or(0),
             original_startline,
             member.startline as usize,
             member.endline as usize,
-        ),
+        )),
         parameters: frame.parameters,
         method_synthesized: member.is_synthesized(),
     })
@@ -1207,7 +1208,7 @@ com.example.MainFragment$onActivityCreated$4 -> com.example.MainFragment$g:
                 StackFrame {
                     class: "com.example.MainFragment$g",
                     method: "onClick",
-                    line: 2,
+                    line: Some(2),
                     file: Some(Cow::Borrowed("SourceFile")),
                     parameters: None,
                     method_synthesized: false,
@@ -1215,7 +1216,7 @@ com.example.MainFragment$onActivityCreated$4 -> com.example.MainFragment$g:
                 StackFrame {
                     class: "android.view.View",
                     method: "performClick",
-                    line: 7393,
+                    line: Some(7393),
                     file: Some(Cow::Borrowed("View.java")),
                     parameters: None,
                     method_synthesized: false,
@@ -1229,7 +1230,7 @@ com.example.MainFragment$onActivityCreated$4 -> com.example.MainFragment$g:
                 frames: vec![StackFrame {
                     class: "com.example.MainFragment$g",
                     method: "onClick",
-                    line: 1,
+                    line: Some(1),
                     file: Some(Cow::Borrowed("SourceFile")),
                     parameters: None,
                     method_synthesized: false,
@@ -1421,7 +1422,7 @@ some.Other -> b:
                 StackFrame {
                     class: "a",
                     method: "call",
-                    line: 4,
+                    line: Some(4),
                     file: Some(Cow::Borrowed("SourceFile")),
                     parameters: None,
                     method_synthesized: false,
@@ -1429,7 +1430,7 @@ some.Other -> b:
                 StackFrame {
                     class: "b",
                     method: "run",
-                    line: 5,
+                    line: Some(5),
                     file: Some(Cow::Borrowed("SourceFile")),
                     parameters: None,
                     method_synthesized: false,
@@ -1445,6 +1446,6 @@ some.Other -> b:
         assert_eq!(remapped.frames.len(), 1);
         assert_eq!(remapped.frames[0].class, "some.Other");
         assert_eq!(remapped.frames[0].method, "method");
-        assert_eq!(remapped.frames[0].line, 30);
+        assert_eq!(remapped.frames[0].line, Some(30));
     }
 }
diff --git a/src/mapper.rs b/src/mapper.rs
index 4e419ed..6f7e18e 100644
--- a/src/mapper.rs
+++ b/src/mapper.rs
@@ -140,7 +140,8 @@ fn map_member_with_lines<'a>(
     frame: &StackFrame<'a>,
     member: &MemberMapping<'a>,
 ) -> Option<StackFrame<'a>> {
-    if member.endline > 0 && (frame.line < member.startline || frame.line > member.endline) {
+    let frame_line = frame.line.unwrap_or(0);
+    if member.endline > 0 && (frame_line < member.startline || frame_line > member.endline) {
         return None;
     }
 
@@ -151,7 +152,7 @@ fn map_member_with_lines<'a>(
     {
         member.original_startline
     } else {
-        member.original_startline + frame.line - member.startline
+        member.original_startline + frame_line - member.startline
     };
 
     let class = member.original_class.unwrap_or(frame.class);
@@ -172,7 +173,7 @@ fn map_member_with_lines<'a>(
         class,
         method: member.original,
         file,
-        line,
+        line: Some(line),
         parameters: frame.parameters,
         method_synthesized: member.is_synthesized,
     })
@@ -191,7 +192,7 @@ fn map_member_without_lines<'a>(
         None
     };
     let line = resolve_no_line_output_line(
-        frame.line,
+        frame.line.unwrap_or(0),
         original_startline,
         member.startline,
         member.endline,
@@ -202,7 +203,7 @@ fn map_member_without_lines<'a>(
         file,
         // Preserve input line if present (e.g. "Unknown Source:7") when the mapping itself
         // has no line information. This matches R8 retrace behavior.
-        line,
+        line: Some(line),
         parameters: frame.parameters,
         method_synthesized: member.is_synthesized,
     }
@@ -214,7 +215,7 @@ fn remap_class_only<'a>(frame: &StackFrame<'a>, reference_file: Option<&str>) ->
         class: frame.class,
         method: frame.method,
         file,
-        line: frame.line,
+        line: Some(frame.line.unwrap_or(0)),
         parameters: frame.parameters,
         method_synthesized: false,
     }
@@ -295,9 +296,10 @@ fn iterate_with_lines<'a>(
     members: &mut core::slice::Iter<'_, MemberMapping<'a>>,
     has_line_info: bool,
 ) -> Option<StackFrame<'a>> {
+    let frame_line = frame.line.unwrap_or(0);
     for member in members {
         // If this method has line mappings, skip base (no-line) entries when we have a concrete line.
-        if has_line_info && frame.line > 0 && member.endline == 0 {
+        if has_line_info && frame_line > 0 && member.endline == 0 {
             continue;
         }
         // If the mapping entry has no line range, preserve the input line number (if any).
@@ -522,11 +524,11 @@ impl<'s> ProguardMapper<'s> {
             if let Some(mapped) = self.map_outline_position(
                 effective.class,
                 effective.method,
-                effective.line,
+                effective.line.unwrap_or(0),
                 pos,
                 effective.parameters,
             ) {
-                effective.line = mapped;
+                effective.line = Some(mapped);
             }
         }
 
@@ -584,7 +586,7 @@ impl<'s> ProguardMapper<'s> {
 
             // If the stacktrace has no line number, treat it as unknown and remap without
             // applying line filters. If there are base (no-line) mappings present, prefer those.
-            if frame.line == 0 {
+            if frame.line.unwrap_or(0) == 0 {
                 let selection = select_no_line_members(mapping_entries, has_line_info);
                 match selection {
                     Some(NoLineSelection::Single(member)) => {
@@ -744,7 +746,7 @@ impl<'s> ProguardMapper<'s> {
 
             if let Some(frame) = stacktrace::parse_frame(line) {
                 if self.is_outline_frame(frame.class, frame.method) {
-                    carried_outline_pos = Some(frame.line);
+                    carried_outline_pos = Some(frame.line.unwrap_or(0));
                     continue;
                 }
 
@@ -810,7 +812,7 @@ impl<'s> ProguardMapper<'s> {
         let mut next_frame_can_rewrite = exception_descriptor.is_some();
         for f in trace.frames.iter() {
             if self.is_outline_frame(f.class, f.method) {
-                carried_outline_pos = Some(f.line);
+                carried_outline_pos = Some(f.line.unwrap_or(0));
                 continue;
             }
 
@@ -913,7 +915,7 @@ com.example.MainFragment$onActivityCreated$4 -> com.example.MainFragment$g:
                 StackFrame {
                     class: "com.example.MainFragment$g",
                     method: "onClick",
-                    line: 2,
+                    line: Some(2),
                     file: Some(Cow::Borrowed("SourceFile")),
                     parameters: None,
                     method_synthesized: false,
@@ -921,7 +923,7 @@ com.example.MainFragment$onActivityCreated$4 -> com.example.MainFragment$g:
                 StackFrame {
                     class: "android.view.View",
                     method: "performClick",
-                    line: 7393,
+                    line: Some(7393),
                     file: Some(Cow::Borrowed("View.java")),
                     parameters: None,
                     method_synthesized: false,
@@ -935,7 +937,7 @@ com.example.MainFragment$onActivityCreated$4 -> com.example.MainFragment$g:
                 frames: vec![StackFrame {
                     class: "com.example.MainFragment$g",
                     method: "onClick",
-                    line: 1,
+                    line: Some(1),
                     file: Some(Cow::Borrowed("SourceFile")),
                     parameters: None,
                     method_synthesized: false,
@@ -1055,7 +1057,7 @@ some.Class -> a:
             frames: vec![StackFrame {
                 class: "a",
                 method: "a",
-                line: 4,
+                line: Some(4),
                 file: Some(Cow::Borrowed("SourceFile")),
                 parameters: None,
                 method_synthesized: false,
@@ -1069,7 +1071,7 @@ some.Class -> a:
         assert_eq!(remapped.frames.len(), 1);
         assert_eq!(remapped.frames[0].class, "some.Class");
         assert_eq!(remapped.frames[0].method, "caller");
-        assert_eq!(remapped.frames[0].line, 7);
+        assert_eq!(remapped.frames[0].line, Some(7));
     }
 
     #[test]
@@ -1176,7 +1178,7 @@ some.Other -> b:
                 StackFrame {
                     class: "a",
                     method: "call",
-                    line: 4,
+                    line: Some(4),
                     file: Some(Cow::Borrowed("SourceFile")),
                     parameters: None,
                     method_synthesized: false,
@@ -1184,7 +1186,7 @@ some.Other -> b:
                 StackFrame {
                     class: "b",
                     method: "run",
-                    line: 5,
+                    line: Some(5),
                     file: Some(Cow::Borrowed("SourceFile")),
                     parameters: None,
                     method_synthesized: false,
@@ -1200,6 +1202,6 @@ some.Other -> b:
         assert_eq!(remapped.frames.len(), 1);
         assert_eq!(remapped.frames[0].class, "some.Other");
         assert_eq!(remapped.frames[0].method, "method");
-        assert_eq!(remapped.frames[0].line, 30);
+        assert_eq!(remapped.frames[0].line, Some(30));
     }
 }
diff --git a/src/stacktrace.rs b/src/stacktrace.rs
index 9e56806..053ade1 100644
--- a/src/stacktrace.rs
+++ b/src/stacktrace.rs
@@ -154,7 +154,7 @@ fn parse_stacktrace(content: &str) -> Option<StackTrace<'_>> {
 pub struct StackFrame<'s> {
     pub(crate) class: &'s str,
     pub(crate) method: &'s str,
-    pub(crate) line: usize,
+    pub(crate) line: Option<usize>,
     pub(crate) file: Option<Cow<'s, str>>,
     pub(crate) parameters: Option<&'s str>,
     pub(crate) method_synthesized: bool,
@@ -166,7 +166,7 @@ impl<'s> StackFrame<'s> {
         Self {
             class,
             method,
-            line,
+            line: Some(line),
             file: None,
             parameters: None,
             method_synthesized: false,
@@ -178,7 +178,7 @@ impl<'s> StackFrame<'s> {
         Self {
             class,
             method,
-            line,
+            line: Some(line),
             file: Some(Cow::Borrowed(file)),
             parameters: None,
             method_synthesized: false,
@@ -191,7 +191,7 @@ impl<'s> StackFrame<'s> {
         Self {
             class,
             method,
-            line: 0,
+            line: None,
             file: None,
             parameters: Some(arguments),
             method_synthesized: false,
@@ -248,7 +248,9 @@ impl<'s> StackFrame<'s> {
     }
 
     /// The line of the StackFrame, 1-based.
-    pub fn line(&self) -> usize {
+    ///
+    /// Returns `None` if the frame has no line information.
+    pub fn line(&self) -> Option<usize> {
         self.line
     }
 
@@ -266,11 +268,14 @@ impl<'s> StackFrame<'s> {
 impl Display for StackFrame<'_> {
     fn fmt(&self, f: &mut Formatter<'_>) -> FmtResult {
         let file_name = self.file.as_deref().unwrap_or("<unknown>");
-        write!(
-            f,
-            "at {}.{}({}:{})",
-            self.class, self.method, file_name, self.line
-        )
+        match self.line {
+            Some(line) => write!(
+                f,
+                "at {}.{}({}:{})",
+                self.class, self.method, file_name, line
+            ),
+            None => write!(f, "at {}.{}({})", self.class, self.method, file_name),
+        }
     }
 }
 
@@ -287,8 +292,8 @@ pub(crate) fn parse_frame(line: &str) -> Option<StackFrame<'_>> {
     let (method_split, file_split) = line[3..line.len() - 1].split_once('(')?;
     let (class, method) = method_split.rsplit_once('.')?;
     let (file, line) = match file_split.rsplit_once(':') {
-        Some((file, line)) => (file, line.parse().unwrap_or(0)),
-        None => (file_split, 0),
+        Some((file, line)) => (file, Some(line.parse().unwrap_or(0))),
+        None => (file_split, None),
     };
 
     Some(StackFrame {
@@ -402,7 +407,7 @@ mod tests {
             frames: vec![StackFrame {
                 class: "com.example.Util",
                 method: "show",
-                line: 5,
+                line: Some(5),
                 file: Some(Cow::Borrowed("Util.java")),
                 parameters: None,
                 method_synthesized: false,
@@ -415,7 +420,7 @@ mod tests {
                 frames: vec![StackFrame {
                     class: "com.example.Parser",
                     method: "parse",
-                    line: 115,
+                    line: Some(115),
                     file: None,
                     parameters: None,
                     method_synthesized: false,
@@ -439,7 +444,7 @@ Caused by: com.example.Other: Invalid data
         let expect = Some(StackFrame {
             class: "com.example.MainFragment",
             method: "onClick",
-            line: 1,
+            line: Some(1),
             file: Some(Cow::Borrowed("SourceFile")),
             parameters: None,
             method_synthesized: false,
@@ -463,7 +468,7 @@ Caused by: com.example.Other: Invalid data
         let frame = StackFrame {
             class: "com.example.MainFragment",
             method: "onClick",
-            line: 1,
+            line: Some(1),
             file: None,
             parameters: None,
             method_synthesized: false,
@@ -477,7 +482,7 @@ Caused by: com.example.Other: Invalid data
         let frame = StackFrame {
             class: "com.example.MainFragment",
             method: "onClick",
-            line: 1,
+            line: Some(1),
             file: Some(Cow::Borrowed("SourceFile")),
             parameters: None,
             method_synthesized: false,
diff --git a/tests/r8-inline.rs b/tests/r8-inline.rs
index 0f70b69..6dc7ac9 100644
--- a/tests/r8-inline.rs
+++ b/tests/r8-inline.rs
@@ -83,13 +83,13 @@ fn test_inline_with_line_numbers_frame() {
 
     assert_eq!(frames.len(), 4);
     assert_eq!(frames[0].method(), "method3");
-    assert_eq!(frames[0].line(), 81);
+    assert_eq!(frames[0].line(), Some(81));
     assert_eq!(frames[1].method(), "method2");
-    assert_eq!(frames[1].line(), 88);
+    assert_eq!(frames[1].line(), Some(88));
     assert_eq!(frames[2].method(), "method1");
-    assert_eq!(frames[2].line(), 96);
+    assert_eq!(frames[2].line(), Some(96));
     assert_eq!(frames[3].method(), "main");
-    assert_eq!(frames[3].line(), 102);
+    assert_eq!(frames[3].line(), Some(102));
 }
 
 // =============================================================================
@@ -493,15 +493,15 @@ fn test_inline_preamble_no_original() {
     let frames: Vec<_> = mapper.remap_frame(&StackFrame::new("a", "a", 2)).collect();
     assert_eq!(frames.len(), 1);
     assert_eq!(frames[0].method(), "caller");
-    assert_eq!(frames[0].line(), 10);
+    assert_eq!(frames[0].line(), Some(10));
 
     // Test line 5 - should be in inline range (4:5)
     let frames: Vec<_> = mapper.remap_frame(&StackFrame::new("a", "a", 5)).collect();
     assert_eq!(frames.len(), 2);
     assert_eq!(frames[0].method(), "inlined");
-    assert_eq!(frames[0].line(), 21);
+    assert_eq!(frames[0].line(), Some(21));
     assert_eq!(frames[1].method(), "caller");
-    assert_eq!(frames[1].line(), 11);
+    assert_eq!(frames[1].line(), Some(11));
 }
 
 // =============================================================================
@@ -580,15 +580,15 @@ fn test_inline_frame_depth_one() {
     let frames: Vec<_> = mapper.remap_frame(&StackFrame::new("a", "a", 1)).collect();
     assert_eq!(frames.len(), 1);
     assert_eq!(frames[0].method(), "foo");
-    assert_eq!(frames[0].line(), 10);
+    assert_eq!(frames[0].line(), Some(10));
 
     // Line 2 - one level of inlining
     let frames: Vec<_> = mapper.remap_frame(&StackFrame::new("a", "a", 2)).collect();
     assert_eq!(frames.len(), 2);
     assert_eq!(frames[0].method(), "bar");
-    assert_eq!(frames[0].line(), 20);
+    assert_eq!(frames[0].line(), Some(20));
     assert_eq!(frames[1].method(), "foo");
-    assert_eq!(frames[1].line(), 11);
+    assert_eq!(frames[1].line(), Some(11));
 }
 
 #[test]
@@ -605,11 +605,11 @@ fn test_inline_frame_depth_two() {
     let frames: Vec<_> = mapper.remap_frame(&StackFrame::new("a", "a", 2)).collect();
     assert_eq!(frames.len(), 3);
     assert_eq!(frames[0].method(), "baz");
-    assert_eq!(frames[0].line(), 30);
+    assert_eq!(frames[0].line(), Some(30));
     assert_eq!(frames[1].method(), "bar");
-    assert_eq!(frames[1].line(), 21);
+    assert_eq!(frames[1].line(), Some(21));
     assert_eq!(frames[2].method(), "foo");
-    assert_eq!(frames[2].line(), 11);
+    assert_eq!(frames[2].line(), Some(11));
 }
 
 #[test]
@@ -631,11 +631,11 @@ fn test_inline_frame_depth_two_cache() {
     let frames: Vec<_> = cache.remap_frame(&frame).collect();
     assert_eq!(frames.len(), 3);
     assert_eq!(frames[0].method(), "baz");
-    assert_eq!(frames[0].line(), 30);
+    assert_eq!(frames[0].line(), Some(30));
     assert_eq!(frames[1].method(), "bar");
-    assert_eq!(frames[1].line(), 21);
+    assert_eq!(frames[1].line(), Some(21));
     assert_eq!(frames[2].method(), "foo");
-    assert_eq!(frames[2].line(), 11);
+    assert_eq!(frames[2].line(), Some(11));
 }
 
 // =============================================================================
@@ -655,15 +655,15 @@ fn test_inline_with_line_range() {
     let frames: Vec<_> = mapper.remap_frame(&StackFrame::new("a", "a", 3)).collect();
     assert_eq!(frames.len(), 1);
     assert_eq!(frames[0].method(), "outer");
-    assert_eq!(frames[0].line(), 12); // 10 + (3-1) = 12
+    assert_eq!(frames[0].line(), Some(12)); // 10 + (3-1) = 12
 
     // Line 8 - in inline range
     let frames: Vec<_> = mapper.remap_frame(&StackFrame::new("a", "a", 8)).collect();
     assert_eq!(frames.len(), 2);
     assert_eq!(frames[0].method(), "inner");
-    assert_eq!(frames[0].line(), 22); // 20 + (8-6) = 22
+    assert_eq!(frames[0].line(), Some(22)); // 20 + (8-6) = 22
     assert_eq!(frames[1].method(), "outer");
-    assert_eq!(frames[1].line(), 15);
+    assert_eq!(frames[1].line(), Some(15));
 }
 
 // =============================================================================
@@ -689,15 +689,15 @@ com.example.Main -> a:
 
     assert_eq!(frames[0].class(), "com.example.lib.Library");
     assert_eq!(frames[0].method(), "work");
-    assert_eq!(frames[0].line(), 100);
+    assert_eq!(frames[0].line(), Some(100));
 
     assert_eq!(frames[1].class(), "com.example.util.Utils");
     assert_eq!(frames[1].method(), "helper");
-    assert_eq!(frames[1].line(), 51);
+    assert_eq!(frames[1].line(), Some(51));
 
     assert_eq!(frames[2].class(), "com.example.Main");
     assert_eq!(frames[2].method(), "main");
-    assert_eq!(frames[2].line(), 11);
+    assert_eq!(frames[2].line(), Some(11));
 }
 
 #[test]
@@ -783,7 +783,7 @@ fn test_inline_with_zero_original_line() {
     // Should have 2 frames - the inline chain
     assert_eq!(frames.len(), 2);
     assert_eq!(frames[0].method(), "main");
-    assert_eq!(frames[0].line(), 0);
+    assert_eq!(frames[0].line(), Some(0));
     assert_eq!(frames[1].method(), "caller");
-    assert_eq!(frames[1].line(), 10);
+    assert_eq!(frames[1].line(), Some(10));
 }
diff --git a/tests/r8.rs b/tests/r8.rs
index cfe58b1..c534587 100644
--- a/tests/r8.rs
+++ b/tests/r8.rs
@@ -410,16 +410,16 @@ fn rewrite_frame_complex_stacktrace_typed() {
     assert_eq!(frames.len(), 4);
     assert_eq!(frames[0].class(), "com.example.flow.Initializer");
     assert_eq!(frames[0].method(), "start");
-    assert_eq!(frames[0].line(), 42);
+    assert_eq!(frames[0].line(), Some(42));
     assert_eq!(frames[1].class(), "com.example.flow.StreamRouter$Inline");
     assert_eq!(frames[1].method(), "internalDispatch");
-    assert_eq!(frames[1].line(), 30);
+    assert_eq!(frames[1].line(), Some(30));
     assert_eq!(frames[2].class(), "com.example.flow.StreamRouter");
     assert_eq!(frames[2].method(), "dispatch");
-    assert_eq!(frames[2].line(), 12);
+    assert_eq!(frames[2].line(), Some(12));
     assert_eq!(frames[3].class(), "com.example.flow.UiBridge");
     assert_eq!(frames[3].method(), "render");
-    assert_eq!(frames[3].line(), 200);
+    assert_eq!(frames[3].line(), Some(200));
 
     // Caused by exception (also not in mapping)
     let cause = remapped.cause().unwrap();
@@ -430,10 +430,10 @@ fn rewrite_frame_complex_stacktrace_typed() {
     assert_eq!(cause_frames.len(), 2);
     assert_eq!(cause_frames[0].class(), "com.example.flow.StreamRouter");
     assert_eq!(cause_frames[0].method(), "dispatch");
-    assert_eq!(cause_frames[0].line(), 12);
+    assert_eq!(cause_frames[0].line(), Some(12));
     assert_eq!(cause_frames[1].class(), "com.example.flow.UiBridge");
     assert_eq!(cause_frames[1].method(), "render");
-    assert_eq!(cause_frames[1].line(), 200);
+    assert_eq!(cause_frames[1].line(), Some(200));
 }
 
 #[test]
@@ -541,7 +541,7 @@ fn test_method_with_zero_zero_and_line_specific_mappings() {
     );
     assert_eq!(frame.method(), "obtainDropShadowRenderer-eZhPAX0");
     // Should map to line 70 (from the 1:4: mapping), not line 68 (from the 0:0: mapping)
-    assert_eq!(frame.line(), 70);
+    assert_eq!(frame.line(), Some(70));
     assert_eq!(mapped.next(), None);
 }
 
@@ -574,6 +574,6 @@ fn test_method_with_zero_zero_and_line_specific_mappings_cache() {
     );
     assert_eq!(remapped_frame.method(), "obtainDropShadowRenderer-eZhPAX0");
     // Should map to line 70 (from the 1:4: mapping), not line 68 (from the 0:0: mapping)
-    assert_eq!(remapped_frame.line(), 70);
+    assert_eq!(remapped_frame.line(), Some(70));
     assert_eq!(mapped.next(), None);
 }