diff --git a/cs5300/examples/calc/CMakeLists.txt b/cs5300/examples/calc/CMakeLists.txt
index 3042590..9d1a84c 100644
--- a/cs5300/examples/calc/CMakeLists.txt
+++ b/cs5300/examples/calc/CMakeLists.txt
@@ -20,7 +20,7 @@ set(calc_srcs
 )
 source_group("Calc" FILES ${calc_srcs})
 
-add_executable(calc ${main_srcs})
+add_executable(calc ${calc_srcs})
 
 target_link_libraries(calc  ${FLEX_LIBRARIES} ${BISON_LIBRARIES})
 
diff --git a/cs5300/examples/calc/parser.y b/cs5300/examples/calc/parser.y
index 5db8ed6..eaa1850 100644
--- a/cs5300/examples/calc/parser.y
+++ b/cs5300/examples/calc/parser.y
@@ -1,6 +1,10 @@
 %{
 #include <iostream>
 extern int yylex();
+void yyerror (char const *s) 
+{
+	std::fprintf (stderr, "%s\n", s);
+}
 %}
 
 %union