diff --git a/test/udev-test.pl b/test/udev-test.pl
index 096977a611..95f9af0e2b 100755
--- a/test/udev-test.pl
+++ b/test/udev-test.pl
@@ -1663,10 +1663,11 @@ EOF
 		exp_name	=> "sda-8741C4G-end",
 		exp_perms	=> "0:0:0660",
 		rules		=> <<EOF
+KERNEL=="sda", PROGRAM="/bin/true create-envp"
+KERNEL=="sda", ENV{TESTENV}="change-envp"
 KERNEL=="sda", NAME="%k-%s{[dmi/id]product_name}-end", RUN+="socket:@/org/kernel/udev/monitor"
 EOF
 	},
-
 );
 
 # set env
diff --git a/udev/lib/libudev-device.c b/udev/lib/libudev-device.c
index bad6e94de5..11a6037d1b 100644
--- a/udev/lib/libudev-device.c
+++ b/udev/lib/libudev-device.c
@@ -1025,8 +1025,8 @@ static int update_envp_monitor_buf(struct udev_device *udev_device)
 		return -ENOMEM;
 
 	/* envp array, strings will point into monitor buffer */
-	free(udev_device->envp);
-	udev_device->envp = malloc(sizeof(char *) * ENVP_SIZE);
+	if (udev_device->envp == NULL)
+		udev_device->envp = malloc(sizeof(char *) * ENVP_SIZE);
 	if (udev_device->envp == NULL)
 		return -ENOMEM;