diff --git a/testsuite/reftests/reftests-dark.test.in b/testsuite/reftests/reftests-dark.test.in
index da32518dad..ea3b40981f 100644
--- a/testsuite/reftests/reftests-dark.test.in
+++ b/testsuite/reftests/reftests-dark.test.in
@@ -1,3 +1,3 @@
 [Test]
-Exec=/bin/sh -c "GTK_THEME=Adwaita:dark @libexecdir@/installed-tests/gtk+/gtk-reftest -k --verbose --output $(pwd) --directory @libexecdir@/installed-tests/gtk+/reftests"
+Exec=/bin/sh -c "env GTK_THEME=Adwaita:dark G_ENABLE_DIAGNOSTIC=0 @libexecdir@/installed-tests/gtk+/gtk-reftest -k --verbose --output $(pwd) --directory @libexecdir@/installed-tests/gtk+/reftests"
 Type=session-exclusive
diff --git a/testsuite/reftests/reftests-hc.test.in b/testsuite/reftests/reftests-hc.test.in
index c69d2490c0..74751619d4 100644
--- a/testsuite/reftests/reftests-hc.test.in
+++ b/testsuite/reftests/reftests-hc.test.in
@@ -1,3 +1,3 @@
 [Test]
-Exec=/bin/sh -c "GTK_THEME=HighContrast @libexecdir@/installed-tests/gtk+/gtk-reftest -k --verbose --output $(pwd) --directory @libexecdir@/installed-tests/gtk+/reftests"
+Exec=/bin/sh -c "env GTK_THEME=HighContrast G_ENABLE_DIAGNOSTIC=0 @libexecdir@/installed-tests/gtk+/gtk-reftest -k --verbose --output $(pwd) --directory @libexecdir@/installed-tests/gtk+/reftests"
 Type=session-exclusive
diff --git a/testsuite/reftests/reftests.test.in b/testsuite/reftests/reftests.test.in
index 53b451fe02..0c4d596192 100644
--- a/testsuite/reftests/reftests.test.in
+++ b/testsuite/reftests/reftests.test.in
@@ -1,3 +1,3 @@
 [Test]
-Exec=/bin/sh -c "@libexecdir@/installed-tests/gtk+/gtk-reftest -k --verbose --output $(pwd) --directory @libexecdir@/installed-tests/gtk+/reftests"
+Exec=/bin/sh -c "env G_ENABLE_DIAGNOSTIC=0 @libexecdir@/installed-tests/gtk+/gtk-reftest -k --verbose --output $(pwd) --directory @libexecdir@/installed-tests/gtk+/reftests"
 Type=session-exclusive