diff --git a/src/syncterm/st_crypt.h b/src/syncterm/st_crypt.h
index 5b90a4bdf5edb89963db0abad9a0a261fb469a2d..d2a65515cdd507d47ff2b97414330d66ee831134 100644
--- a/src/syncterm/st_crypt.h
+++ b/src/syncterm/st_crypt.h
@@ -3,6 +3,11 @@
 
 #include"cryptlib.h"
 
+#if defined(_MSC_VER)
+	#undef C_RET 
+	#define C_RET int
+#endif
+
 struct crypt_funcs {
 	C_RET (*PopData)( C_IN CRYPT_HANDLE envelope, C_OUT void C_PTR buffer,
 		C_IN int length, C_OUT int C_PTR bytesCopied );