diff --git a/testsuite/gdk/gdk.test.in b/testsuite/gdk/gdk.test.in
index 9784de8542..b766ceb9b6 100644
--- a/testsuite/gdk/gdk.test.in
+++ b/testsuite/gdk/gdk.test.in
@@ -1,4 +1,4 @@
 [Test]
-Exec=/bin/sh -c "env G_ENABLE_DIAGNOSTIC=0 GTK_A11Y=test @testexecdir@/@test@ --tap -k --verbose"
+Exec=/bin/sh -c "env GDK_DEBUG=clipboard G_ENABLE_DIAGNOSTIC=0 GTK_A11Y=test @testexecdir@/@test@ --tap -k --verbose"
 Type=session
 Output=TAP