--- graphviz-2.44.1/cmd/smyrna/gui/gui.c.orig	2020-10-31 13:38:12.816276500 +0300
+++ graphviz-2.44.1/cmd/smyrna/gui/gui.c	2020-10-31 13:38:19.828189300 +0300
@@ -25,7 +25,7 @@
 
 static char guibuffer[BUFSIZ];	//general purpose buffer
 
-#ifdef _WIN32
+#ifdef _MSC_VER
 extern int strcasecmp(const char *s1, const char *s2);
 extern int strncasecmp(const char *s1, const char *s2, unsigned int n);
 #endif