diff --git a/pcap-stdinc.h b/pcap-stdinc.h
index fa5ea26..1281024 100644
--- a/pcap-stdinc.h
+++ b/pcap-stdinc.h
@@ -33,6 +33,9 @@
 #define SIZEOF_CHAR 1
 #define SIZEOF_SHORT 2
 #define SIZEOF_INT 4
+#ifndef _MSC_EXTENSIONS
+#define SIZEOF_LONG_LONG 8
+#endif
 
 /*
  * Avoids a compiler warning in case this was already defined