diff --git a/common/src/test/java/io/smallrye/config/common/utils/StringUtilTest.java b/common/src/test/java/io/smallrye/config/common/utils/StringUtilTest.java
index 6aca90dfe..ebc856325 100644
--- a/common/src/test/java/io/smallrye/config/common/utils/StringUtilTest.java
+++ b/common/src/test/java/io/smallrye/config/common/utils/StringUtilTest.java
@@ -17,6 +17,7 @@
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
 import org.junit.jupiter.api.Test;
@@ -186,6 +187,7 @@ void toLowerCaseAndDotted() {
         assertEquals("test.language.\"de.etr\"", StringUtil.toLowerCaseAndDotted("TEST_LANGUAGE__DE_ETR__"));
         assertEquals("%foo.bar", StringUtil.toLowerCaseAndDotted("_FOO_BAR"));
         assertEquals(".\"foo.bar", StringUtil.toLowerCaseAndDotted("__FOO_BAR"));
+        assertNotNull(StringUtil.toLowerCaseAndDotted("00_PYTHON_2_7"));
     }
 
     @Test