diff --git a/tests/testdisplay.c b/tests/testdisplay.c
index c8cdb204..2793a4be 100644
--- a/tests/testdisplay.c
+++ b/tests/testdisplay.c
@@ -819,6 +819,9 @@ disable_planes(int fd)
 }
 #else
 static void enable_plane(struct connector *c) { return; }
+static void
+adjust_plane(int fd, int xdistance, int ydistance, int wdiff, int hdiff)
+{ return; }
 static void disable_planes(int fd) { return; }
 #endif