diff --git a/tests/test_flock.sh b/tests/test_flock.sh
new file mode 100644
index 000000000..162d6feff
--- /dev/null
+++ b/tests/test_flock.sh
@@ -0,0 +1,30 @@
+#!/usr/bin/env sh
+
+#
+# Ensure umu-launcher does not download its fetched resources more than once
+# when multiple processes of itself are created
+#
+
+tmp1=$(mktemp)
+tmp2=$(mktemp)
+
+UMU_LOG=debug GAMEID=umu-0 "$HOME/.local/bin/umu-run" wineboot -u 2> "$tmp1" &
+sleep 1
+UMU_LOG=debug GAMEID=umu-0 "$HOME/.local/bin/umu-run" wineboot -u 2> "$tmp2" &
+wait
+
+grep "exited with wait status" "$tmp1"
+
+# Ensure the 2nd proc didn't download the runtime
+grep "\(latest\), please wait..." "$tmp2" 
+if [ $? -ne 0 ]; then
+	exit 1
+fi
+
+grep "exited with wait status" "$tmp2"
+
+# Ensure the 2nd proc didn't download Proton
+grep "Downloading" "$tmp2" 
+if [ $? -ne 0 ]; then
+	exit 1
+fi