diff --git a/src/lib/winpcap/bittypes.h b/src/lib/winpcap/bittypes.h
index 558a0b5c0d8..c9d3b177c09 100644
--- a/src/lib/winpcap/bittypes.h
+++ b/src/lib/winpcap/bittypes.h
@@ -69,7 +69,7 @@ typedef signed char int16_t;
 #if SIZEOF_INT == 4
 typedef unsigned int u_int32_t;
 typedef signed int int32_t;
-#elif SIZEOF_LONG == 4
+#elif defined(SIZEOF_LONG) && (SIZEOF_LONG == 4)
 typedef unsigned long u_int32_t;
 typedef signed long int32_t;
 #elif SIZEOF_SHORT == 4
@@ -92,7 +92,7 @@ typedef unsigned _int64 u_int64_t;
 typedef _int64 int64_t;
 #elif SIZEOF_INT == 8
 typedef unsigned int u_int64_t;
-#elif SIZEOF_LONG == 8
+#elif defined(SIZEOF_LONG) && (SIZEOF_LONG == 8)
 typedef unsigned long u_int64_t;
 #elif SIZEOF_SHORT == 8
 typedef unsigned short u_int64_t;
diff --git a/src/lib/winpcap/pcap-stdinc.h b/src/lib/winpcap/pcap-stdinc.h
index 624d5c2d2a6..eb751d4433c 100644
--- a/src/lib/winpcap/pcap-stdinc.h
+++ b/src/lib/winpcap/pcap-stdinc.h
@@ -60,13 +60,13 @@
 
 #define caddr_t char*
 
-#if _MSC_VER < 1500
+#if defined(_MSC_VER) && (__MSC_VER < 1500)
 #define snprintf _snprintf
 #define vsnprintf _vsnprintf
 #define strdup _strdup
 #endif
 
-#if _MSC_VER < 1700
+#if defined(_MSC_VER) && (__MSC_VER < 1700)
 #define inline __inline 
 #endif