diff --git a/src/Utils.cpp b/src/Utils.cpp
index 6411bd68..bfa1a7ff 100644
--- a/src/Utils.cpp
+++ b/src/Utils.cpp
@@ -14,10 +14,12 @@
  * limitations under the License.
  */
 
+#ifdef __CYGWIN__
 #ifndef _XOPEN_SOURCE
 // strptime() wants this
 #define _XOPEN_SOURCE 600
 #endif
+#endif
 
 #include <znc/Utils.h>
 #include <znc/ZNCDebug.h>