diff --git a/src/util-strings.c b/src/util-strings.c
index b721bd9..d013717 100644
--- a/src/util-strings.c
+++ b/src/util-strings.c
@@ -28,6 +28,7 @@
 #include <string.h>
 
 #include "util-strings.h"
+#include "util-io.h"
 
 /**
  * Return the next word in a string pointed to by state before the first
@@ -516,7 +517,7 @@ MUNIT_TEST(test_cmdline_as_str)
 
 	xsnprintf(cmdline, sizeof(cmdline), "/proc/%i/cmdline", getpid());
 
-	int fd = open(cmdline, O_RDONLY);
+	_cleanup_close_ int fd = open(cmdline, O_RDONLY);
 	munit_assert_int(fd, >=, 0);
 	int len = read(fd, cmdline, sizeof(cmdline) - 1);
 	munit_assert_int(len, >=, 0);