diff --git a/modules/mod-test/Makefile b/modules/mod-test/Makefile
index 79a88725d08..1b74f477ac9 100644
--- a/modules/mod-test/Makefile
+++ b/modules/mod-test/Makefile
@@ -28,9 +28,9 @@ LDFLAGS =
 SO      = so
 # -fPIC is a no-op on Windows, but causes a compiler warning
 ifeq ($(SO),dll)
-CFLAGS  = -ggdb3 -Wall
+CFLAGS  = -std=gnu99 -ggdb3 -Wall
 else
-CFLAGS  = -ggdb3 -Wall -fPIC
+CFLAGS  = -std=gnu99 -ggdb3 -Wall -fPIC
 endif
 
 all: mod-test.$(SO)
diff --git a/modules/mod-test/mod-test.c b/modules/mod-test/mod-test.c
index 0160da69d0f..bae1967f533 100644
--- a/modules/mod-test/mod-test.c
+++ b/modules/mod-test/mod-test.c
@@ -19,6 +19,7 @@ along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
 
 #include <assert.h>
 #include <stdio.h>
+#include <stdlib.h>
 #include <emacs-module.h>
 
 int plugin_is_GPL_compatible;