diff --git a/config.c b/config.c
index 15c08bc..ed7f052 100644
--- a/config.c
+++ b/config.c
@@ -34,8 +34,7 @@
 
 #include "config.h"
 #include "config-internal.h"
-
-#define ARRAY_SIZE(a) (sizeof(a) / sizeof((a)[0]))
+#include "util.h"
 
 static const char *config_default_filename = SYSCONFDIR "/obmc-console.conf";
 
diff --git a/console-server.h b/console-server.h
index cc92101..ac827c8 100644
--- a/console-server.h
+++ b/console-server.h
@@ -232,8 +232,6 @@
 /* socket-handler API */
 int dbus_create_socket_consumer(struct console *console);
 
-#define ARRAY_SIZE(a) (sizeof(a) / sizeof((a)[0]))
-
 #ifndef offsetof
 #define offsetof(type, member) ((unsigned long)&((type *)NULL)->member)
 #endif
diff --git a/test/test-client-escape.c b/test/test-client-escape.c
index b3083b7..e8020f7 100644
--- a/test/test-client-escape.c
+++ b/test/test-client-escape.c
@@ -21,6 +21,8 @@
 #include <stdio.h>
 #include <unistd.h>
 
+#include "util.h"
+
 static ssize_t __read(int fd, void *buf, size_t len);
 #define read __read
 #include "config.c"
@@ -154,8 +156,6 @@
 	},
 };
 
-#define ARRAY_SIZE(a) (sizeof(a) / sizeof((a)[0]))
-
 struct test_ctx ctxs[ARRAY_SIZE(tests)];
 
 int write_buf_to_fd(int fd, const uint8_t *buf, size_t len)
diff --git a/util.h b/util.h
new file mode 100644
index 0000000..01a23d7
--- /dev/null
+++ b/util.h
@@ -0,0 +1,19 @@
+/**
+ * Copyright © 2024 9elements
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#define ARRAY_SIZE(a) (sizeof(a) / sizeof((a)[0]))