diff --git a/Tests/COnly/libc2.c b/Tests/COnly/libc2.c
index 9a6183739..0fd895664 100644
--- a/Tests/COnly/libc2.c
+++ b/Tests/COnly/libc2.c
@@ -1,3 +1,5 @@
+#include "libc2.h"
+
 float LibC2Func()
 {
   return 1.0;
diff --git a/Tests/COnly/libc2.h b/Tests/COnly/libc2.h
index c2d47e5fd..bc26e0120 100644
--- a/Tests/COnly/libc2.h
+++ b/Tests/COnly/libc2.h
@@ -1 +1,11 @@
-extern float LibC2Func();
+#ifdef _WIN32
+#  ifdef c2_EXPORTS
+#    define CM_TEST_LIB_EXPORT  __declspec( dllexport )
+#  else
+#    define CM_TEST_LIB_EXPORT  __declspec( dllimport )
+#  endif
+#else
+#  define CM_TEST_LIB_EXPORT 
+#endif
+
+CM_TEST_LIB_EXPORT float LibC2Func();