diff --git a/virtdata-lib-basics/src/test/java/io/nosqlbench/virtdata/library/basics/shared/from_long/to_string/ConcatTest.java b/virtdata-lib-basics/src/test/java/io/nosqlbench/virtdata/library/basics/shared/from_long/to_string/ConcatTest.java
index 12bea5735..ae39c8ab4 100644
--- a/virtdata-lib-basics/src/test/java/io/nosqlbench/virtdata/library/basics/shared/from_long/to_string/ConcatTest.java
+++ b/virtdata-lib-basics/src/test/java/io/nosqlbench/virtdata/library/basics/shared/from_long/to_string/ConcatTest.java
@@ -32,7 +32,8 @@ class ConcatTest {
 
     @Test
     public void testMismatchedInserts() {
-        assertThrows(RuntimeException.class, () -> new Concat((c, s) -> c+s, "{}"));
+        Concat c = new Concat("{}");
+        assertThat(c.apply(3L)).isEqualTo("v:3");
     }
 
     @Test