diff --git a/tests/test-lib.sh b/tests/test-lib.sh
index 77f1f41..086d12c 100644
--- a/tests/test-lib.sh
+++ b/tests/test-lib.sh
@@ -36,6 +36,9 @@ VISUAL=:
 # CDPATH into the environment
 unset CDPATH
 
+# Protect ourselves from using predefined TODOTXT_CFG_FILE
+unset TODOTXT_CFG_FILE
+
 # Each test should start with something like this, after copyright notices:
 #
 # test_description='Description of this test...