diff --git a/include/types/buffers.h b/include/types/buffers.h
index 133285f..fc070bd 100644
--- a/include/types/buffers.h
+++ b/include/types/buffers.h
@@ -149,7 +149,7 @@
 struct chunk {
 	char *str;	/* beginning of the string itself. Might not be 0-terminated */
 	size_t size;	/* total size of the buffer, 0 if the *str is read-only */
-	size_t len;	/* current size of the string from first to last char. <0 = uninit. */
+	int len;	/* current size of the string from first to last char. <0 = uninit. */
 };
 
 /* needed for a declaration below */