diff -ur pmx-2.7.0.orig/libf2c/signal_.c pmx-2.7.0/libf2c/signal_.c
--- pmx-2.7.0.orig/libf2c/signal_.c	2013-03-12 18:54:34.000000000 +0100
+++ pmx-2.7.0/libf2c/signal_.c	2014-11-25 09:31:31.000000000 +0100
@@ -14,7 +14,11 @@
 	int sig;
 	sig = (int)*sigp;
 
-	return (ftnint)signal(sig, proc);
+#ifdef _WIN64
+	return (ftnint)(__int64)signal(sig, proc);
+#else
+	return (ftnint)(long)signal(sig, proc);
+#endif
 	}
 #ifdef __cplusplus
 }
