diff --git a/include/shmlog.h b/include/shmlog.h
new file mode 100644
index 00000000..c513babf
--- /dev/null
+++ b/include/shmlog.h
@@ -0,0 +1,22 @@
+/*
+ * vim:ts=4:sw=4:expandtab
+ *
+ * i3 - an improved dynamic tiling window manager
+ * © 2009-2012 Michael Stapelberg and contributors (see also: LICENSE)
+ *
+ * The format of the shmlog data structure which i3 development versions use by
+ * default (ringbuffer for storing the debug log).
+ *
+ */
+#ifndef _I3_SHMLOG_H
+#define _I3_SHMLOG_H
+
+#include <stdint.h>
+
+typedef struct i3_shmlog_header {
+    uint32_t offset_next_write;
+    uint32_t offset_last_wrap;
+    uint32_t size;
+} i3_shmlog_header;
+
+#endif