diff --git a/man.spec b/man.spec
index c125d49..99525c1 100644
--- a/man.spec
+++ b/man.spec
@@ -123,7 +123,7 @@ Authors:
     rm -f configure
 %global optflags %{optflags} -funroll-loops -pipe -Wall
     if grep -q _DEFAULT_SOURCE /usr/include/features.h ; then
-	CFLAGS="%{optflags} -D_DEFAULT_SOURCE"
+	CFLAGS="%{optflags} -D_GNU_SOURCE -D_DEFAULT_SOURCE"
     else
 	CFLAGS="%{optflags} -D_GNU_SOURCE -D_SVID_SOURCE"
     fi