diff --git a/src/processor/basic_source_line_resolver.cc b/src/processor/basic_source_line_resolver.cc
index 62aa4138..10dcb276 100644
--- a/src/processor/basic_source_line_resolver.cc
+++ b/src/processor/basic_source_line_resolver.cc
@@ -56,7 +56,9 @@ using std::make_pair;
 namespace google_breakpad {
 
 #ifdef _WIN32
+#ifdef _MSC_VER
 #define strtok_r strtok_s
+#endif
 #define strtoull _strtoui64
 #endif
 
diff --git a/src/processor/cfi_frame_info.cc b/src/processor/cfi_frame_info.cc
index 5106ba09..0c4af7ba 100644
--- a/src/processor/cfi_frame_info.cc
+++ b/src/processor/cfi_frame_info.cc
@@ -43,7 +43,7 @@
 
 namespace google_breakpad {
 
-#ifdef _WIN32
+#ifdef _MSC_VER
 #define strtok_r strtok_s
 #endif
 
diff --git a/src/processor/tokenize.cc b/src/processor/tokenize.cc
index f468120c..8fce87a2 100644
--- a/src/processor/tokenize.cc
+++ b/src/processor/tokenize.cc
@@ -36,7 +36,7 @@
 
 namespace google_breakpad {
 
-#ifdef _WIN32
+#ifdef _MSC_VER
 #define strtok_r strtok_s
 #endif