diff --git a/src/common/compat.h b/src/common/compat.h
index 7cfb6a5e45..b7eaf75ea3 100644
--- a/src/common/compat.h
+++ b/src/common/compat.h
@@ -13,7 +13,7 @@
 #define WIN32_WINNT 0x400
 #define _WIN32_WINNT 0x400
 #define WIN32_LEAN_AND_MEAN
-#if (_MSC_VER <= 1300)
+#if defined(_MSC_VER) && (_MSC_VER <= 1300)
 #include <winsock.h>
 #else
 #include <winsock2.h>
diff --git a/src/common/util.c b/src/common/util.c
index b042963c57..a16d41fad7 100644
--- a/src/common/util.c
+++ b/src/common/util.c
@@ -541,7 +541,7 @@ tor_parse_uint64(const char *s, int base, uint64_t min,
 #ifdef HAVE_STRTOULL
   r = (uint64_t)strtoull(s, &endptr, base);
 #elif defined(MS_WINDOWS)
-#if _MSC_VER < 1300
+#if defined(_MSC_VER) && _MSC_VER < 1300
   tor_assert(base <= 10);
   r = (uint64_t)_atoi64(s);
   endptr = (char*)s;
diff --git a/src/tools/tor-resolve.c b/src/tools/tor-resolve.c
index f24bff497b..25a14a4660 100644
--- a/src/tools/tor-resolve.c
+++ b/src/tools/tor-resolve.c
@@ -31,7 +31,7 @@
 #endif
 
 #ifdef MS_WINDOWS
-#if (_MSC_VER <= 1300)
+#if defined(_MSC_VER) && (_MSC_VER <= 1300)
 #include <winsock.h>
 #else
 #include <winsock2.h>