diff --git a/src/jc_test.h b/src/jc_test.h
index a4aaa7a..7208912 100644
--- a/src/jc_test.h
+++ b/src/jc_test.h
@@ -202,18 +202,26 @@ struct jc_test_params_class : public jc_test_base_class {
 #endif
 
 #if !defined(JC_FMT_U64)
-    #if defined(__ANDROID__)
-        #define JC_FMT_U64 "%llu"
-        #define JC_FMT_I64 "%lld"
-    #else
-        #if __cplusplus == 199711L && (defined(__GNUC__) && !defined(__clang__))
-            // For some reason GCC would always warn about the format not working in c++98 (it does though)
-            #pragma GCC diagnostic ignored "-Wformat"
+    #if defined(__has_include)
+        #if __has_include(<inttypes.h>)
+            #include <inttypes.h>
         #endif
-        #include <inttypes.h>
-        #define JC_FMT_U64 "%" PRIu64
-        #define JC_FMT_I64 "%" PRId64
     #endif
+
+    #if !defined(PRId64)
+        #if defined(_MSC_VER)
+            #define PRId64 "I64d"
+            #define PRIi64 "I64i"
+            #define PRIu64 "I64u"
+            #define PRIx64 "I64x"
+        #else
+            #define PRIu64 "llu"
+            #define PRIx64 "lld"
+        #endif
+    #endif
+
+    #define JC_FMT_U64 "%" PRIu64
+    #define JC_FMT_I64 "%" PRId64
 #endif
 
 #if defined(__x86_64__) || defined(__arm64) || defined(__aarch64__) || defined(__ppc64__) || defined(_WIN64)
@@ -1042,7 +1050,7 @@ template <> char* jc_test_print_value(char* buffer, size_t buffer_len, std::null
 
 static int jc_get_formatted_test_name(char* buffer, size_t buffer_len, const jc_test_fixture* fixture, const jc_test_entry* test, int usecolor) {
     if (fixture->index != 0xFFFFFFFF)
-        return JC_TEST_SNPRINTF(buffer, buffer_len, "%s%s%s.%s%s%s/%d", JC_TEST_COL2(CYAN,usecolor), fixture->name, JC_TEST_COL2(DEFAULT,usecolor), JC_TEST_COL2(YELLOW,usecolor), test->name, JC_TEST_COL2(DEFAULT,usecolor), fixture->index);
+        return JC_TEST_SNPRINTF(buffer, buffer_len, "%s%s%s.%s%s%s/%u", JC_TEST_COL2(CYAN,usecolor), fixture->name, JC_TEST_COL2(DEFAULT,usecolor), JC_TEST_COL2(YELLOW,usecolor), test->name, JC_TEST_COL2(DEFAULT,usecolor), fixture->index);
     else
         return JC_TEST_SNPRINTF(buffer, buffer_len, "%s%s%s.%s%s%s", JC_TEST_COL2(CYAN,usecolor), fixture->name, JC_TEST_COL2(DEFAULT,usecolor), JC_TEST_COL2(YELLOW,usecolor), test->name, JC_TEST_COL2(DEFAULT,usecolor));
 }
@@ -1206,7 +1214,7 @@ void jc_test_print_logger::OnTestSetup(const jc_test_fixture* fixture, const jc_
     str->Appendf("%s%s%s", JC_TEST_COL(YELLOW), test->name, JC_TEST_COL(DEFAULT));
 
     if (fixture->index != 0xFFFFFFFF) {
-        str->Appendf("/%d ", fixture->index);
+        str->Appendf("/%u ", fixture->index);
     }
     str->Append("\n");
 
@@ -1219,7 +1227,7 @@ void jc_test_print_logger::OnTestTeardown(const jc_test_fixture* fixture, const
 
     str->Appendf("%s%s%s", JC_TEST_COL(YELLOW), test->name, JC_TEST_COL(DEFAULT));
     if (fixture->index != 0xFFFFFFFF) {
-        str->Appendf("/%d ", fixture->index);
+        str->Appendf("/%u ", fixture->index);
     }
     if (test->fail)
         str->Appendf(" %s%s%s (", JC_TEST_COL(FAIL), "FAIL", JC_TEST_COL(DEFAULT));
@@ -2054,6 +2062,7 @@ INSTANTIATE_TEST_CASE_P(EvenValues, MyParamTest, jc_test_values(2,4,6,8,10));
  *      Made sure to compile with highest warning/error levels possible
  *
  * HISTORY:
+ *      0.12    2025-09-24  * Added more robust way to check for PRIu64 etc
  *      0.11    2023-10-13  * Added JC_TEST_OUTPUT_FN for customizing log output
  *                          * Added JC_TEST_USE_PRINTF to choose printf() over write()
  *      0.10    2023-05-19  * Introduced JC_TEXT_LOGGER_CLASS for easier log printing