diff --git a/testsuite/reftests/reftests.test.in b/testsuite/reftests/reftests.test.in
index bf58d43db1..93632e1c97 100644
--- a/testsuite/reftests/reftests.test.in
+++ b/testsuite/reftests/reftests.test.in
@@ -1,3 +1,3 @@
 [Test]
-Exec=/bin/sh -c "@pkglibexecdir@/installed-tests/gtk-reftest -k --verbose --output $(pwd) --directory @pkglibexecdir@/installed-tests/reftests"
+Exec=/bin/sh -c "GTK_DEBUG=icontheme @pkglibexecdir@/installed-tests/gtk-reftest -k --verbose --output $(pwd) --directory @pkglibexecdir@/installed-tests/reftests"
 Type=session-exclusive