diff --git a/src/util.cpp b/src/util.cpp
index 2eda18048..3670a0193 100644
--- a/src/util.cpp
+++ b/src/util.cpp
@@ -17,8 +17,11 @@
 // clang-format off
 // Dont't remove `format off`, it prevent reordering of win-includes.
 
+#if defined(__MINGW32__) || defined(__MINGW64__) || defined(__CYGWIN__) || \
+    defined(__QNXNTO__)
 #  define _POSIX_C_SOURCE 200809L
 #  define _XOPEN_SOURCE 700L
+#endif
 
 #ifdef _WIN32
 #  ifndef WIN32_LEAN_AND_MEAN