1 files changed, 7 insertions, 0 deletions
diff --git a/src/feh.h b/src/feh.h
index 4e7a3ff..3e0cdda 100644
--- a/src/feh.h
+++ b/src/feh.h
@@ -27,7 +27,14 @@ CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 #ifndef FEH_H
 #define FEH_H
 
+/*
+ * strverscmp(3) is a GNU extension. In most supporting C libraries it
+ * requires _GNU_SOURCE to be defined.
+ */
+#ifdef HAVE_VERSCMP
 #define _GNU_SOURCE
+#endif
+
 #include <X11/Xlib.h>
 #include <X11/Xutil.h>
 #include <X11/Xatom.h>