diff --git a/Makefile b/Makefile
index b245ce225..2570261f0 100644
--- a/Makefile
+++ b/Makefile
@@ -41,16 +41,16 @@ demo:
 	./odin run examples/demo/demo.odin
 
 debug:
-	$(CC) src/main.cpp src/libtommath.c $(DISABLED_WARNINGS) $(CFLAGS) -g $(LDFLAGS) -o odin
+	$(CC) src/main.cpp src/libtommath.cpp $(DISABLED_WARNINGS) $(CFLAGS) -g $(LDFLAGS) -o odin
 
 release:
-	$(CC) src/main.cpp src/libtommath.c $(DISABLED_WARNINGS) $(CFLAGS) -O3 $(LDFLAGS) -o odin
+	$(CC) src/main.cpp src/libtommath.cpp $(DISABLED_WARNINGS) $(CFLAGS) -O3 $(LDFLAGS) -o odin
 
 release_native:
-	$(CC) src/main.cpp src/libtommath.c $(DISABLED_WARNINGS) $(CFLAGS) -O3 -march=native $(LDFLAGS) -o odin
+	$(CC) src/main.cpp src/libtommath.cpp $(DISABLED_WARNINGS) $(CFLAGS) -O3 -march=native $(LDFLAGS) -o odin
 
 nightly:
-	$(CC) src/main.cpp src/libtommath.c $(DISABLED_WARNINGS) $(CFLAGS) -DNIGHTLY -O3 $(LDFLAGS) -o odin
+	$(CC) src/main.cpp src/libtommath.cpp $(DISABLED_WARNINGS) $(CFLAGS) -DNIGHTLY -O3 $(LDFLAGS) -o odin
 
 
 
diff --git a/build.bat b/build.bat
index c3ab0a008..79978015f 100644
--- a/build.bat
+++ b/build.bat
@@ -70,7 +70,7 @@ set linker_settings=%libs% %linker_flags%
 del *.pdb > NUL 2> NUL
 del *.ilk > NUL 2> NUL
 
-cl %compiler_settings% "src\main.cpp" "src\libtommath.c" /link %linker_settings% -OUT:%exe_name%
+cl %compiler_settings% "src\main.cpp" "src\libtommath.cpp" /link %linker_settings% -OUT:%exe_name%
 
 if %errorlevel% neq 0 goto end_of_build
 if %release_mode% EQU 0 odin run examples/demo/demo.odin
diff --git a/src/libtommath.c b/src/libtommath.cpp
similarity index 100%
rename from src/libtommath.c
rename to src/libtommath.cpp