diff --git a/PortMaster/mod_EmuELEC.txt b/PortMaster/mod_EmuELEC.txt
index e384bcc2..429b71c3 100644
--- a/PortMaster/mod_EmuELEC.txt
+++ b/PortMaster/mod_EmuELEC.txt
@@ -18,7 +18,9 @@ GODOT_OPTS="--resolution ${DISPLAY_WIDTH}x${DISPLAY_HEIGHT} -f"
 # no device GUID is known. Ports export it as SDL_GAMECONTROLLERCONFIG, which
 # exceeds MAX_ARG_STRLEN (131072 bytes) and makes every execve() fail with E2BIG.
 # SDL still gets the mappings via SDL_GAMECONTROLLERCONFIG_FILE.
-if declare -f get_controls >/dev/null 2>&1; then
+# Only once: some ports source this file twice, and wrapping the wrapper would make
+# get_controls call itself until bash crashes.
+if declare -f get_controls >/dev/null 2>&1 && ! declare -f _pm_get_controls_orig >/dev/null 2>&1; then
     eval "_pm_get_controls_orig() $(declare -f get_controls | tail -n +2)"
 
     get_controls() {
diff --git a/tests/test_mod_files.py b/tests/test_mod_files.py
new file mode 100644
index 00000000..ca68f340
--- /dev/null
+++ b/tests/test_mod_files.py
@@ -0,0 +1,40 @@
+# SPDX-License-Identifier: MIT
+#
+# mod_<CFW>.txt files, which ports source after control.txt.
+
+import subprocess
+from pathlib import Path
+
+import pytest
+
+PM_DIR = Path(__file__).resolve().parent.parent / "PortMaster"
+
+## get_controls as control.txt's, with no device GUID: the whole gamecontrollerdb.
+FAKE_GET_CONTROLS = 'get_controls() { sdl_controllerconfig="$(printf "%0${SDL_SIZE}d" 0)"; }\n'
+
+
+def run_bash(script, size=200000):
+    result = subprocess.run(
+        ## (No core file if bash does crash.)
+        ["bash", "-c", f'ulimit -c 0\ncontrolfolder="{PM_DIR}"\nSDL_SIZE={size}\n' + FAKE_GET_CONTROLS + script],
+        capture_output=True, text=True, timeout=30)
+    return result
+
+
+@pytest.mark.parametrize("sources", [1, 2, 3])
+def test_emuelec_get_controls_clears_the_whole_db(sources):
+    ## Some ports (Mystik Belle, The Flayed Man, The Sphinx of Time) source it twice: wrapping
+    ## the wrapper made get_controls call itself until bash crashed.
+    result = run_bash(
+        'source "$controlfolder/mod_EmuELEC.txt"\n' * sources +
+        'get_controls\necho "len=${#sdl_controllerconfig}"\n')
+
+    assert result.returncode == 0, result.stderr
+    assert result.stdout.strip() == "len=0"
+
+
+def test_emuelec_get_controls_keeps_a_small_config():
+    ## One device's mappings, as SDL_GAMECONTROLLERCONFIG should have.
+    result = run_bash('source "$controlfolder/mod_EmuELEC.txt"\nget_controls\necho "len=${#sdl_controllerconfig}"\n', size=300)
+
+    assert result.stdout.strip() == "len=300"