diff --git a/openldap.spec b/openldap.spec
index 0915461..dfa634e 100644
--- a/openldap.spec
+++ b/openldap.spec
@@ -229,7 +229,7 @@ if pkg-config openssl ; then
     LDFLAGS="$OPENSSL_LDFLAGS" ; export LDFLAGS
 fi
 CPPFLAGS="-I${dbdir}/include $OPENSSL_CPPFLAGS" ; export CPPFLAGS
-CFLAGS="$CPPFLAGS $RPM_OPT_FLAGS -D_REENTRANT -fPIC"; export CFLAGS
+CFLAGS="$CPPFLAGS $RPM_OPT_FLAGS -D_REENTRANT -fPIC -D_GNU_SOURCE"; export CFLAGS
 LDFLAGS="-L${dbdir}/%{_lib} $OPENSSL_LDFLAGS" ; export LDFLAGS
 LD_LIBRARY_PATH=${dbdir}/%{_lib}${LD_LIBRARY_PATH:+:${LD_LIBRARY_PATH}}; export LD_LIBRARY_PATH