diff --git a/src/part.h b/src/part.h
index 149b06eee885cd2614541f5e2afb2db1b8928266..471700f1542a9cf0dd3807f28363580a43927f51 100644
--- a/src/part.h
+++ b/src/part.h
@@ -33,6 +33,7 @@
 /* Local headers. */
 #include "align.h"
 #include "part_type.h"
+#include "timeline.h"
 
 /* Some constants. */
 #define part_align 128