diff --git a/tests/Makefile b/tests/Makefile
index 34c8f9b..412cb10 100644
--- a/tests/Makefile
+++ b/tests/Makefile
@@ -1,7 +1,9 @@
+INCLUDE = -I..
+
 32:
-	$(CC) -m32 -I.. ../stb_vorbis.c test_c_compilation.c
-	$(CC) -m32 -I.. ../stb_vorbis.c test_cpp_compilation.cpp
+	$(CC) -m32 $(INCLUDE) ../stb_vorbis.c test_c_compilation.c -lm
+	$(CC) -m32 $(INCLUDE) ../stb_vorbis.c test_cpp_compilation.cpp -lm
 
 64:
-	$(CC) -m64 -I.. ../stb_vorbis.c test_c_compilation.c
-	$(CC) -m64 -I.. ../stb_vorbis.c test_cpp_compilation.cpp
+	$(CC) -m64 $(INCLUDE) ../stb_vorbis.c test_c_compilation.c -lm
+	$(CC) -m64 $(INCLUDE) ../stb_vorbis.c test_cpp_compilation.cpp -lm