diff --git a/java/ql/test/kotlin/query-tests/AbstractToConcreteCollection/AbstractToConcreteCollection.expected b/java/ql/test/kotlin/query-tests/AbstractToConcreteCollection/AbstractToConcreteCollection.expected
new file mode 100644
index 00000000000..6160059acfd
--- /dev/null
+++ b/java/ql/test/kotlin/query-tests/AbstractToConcreteCollection/AbstractToConcreteCollection.expected
@@ -0,0 +1 @@
+| Test.kt:3:9:3:9 | <implicit cast> | $@ is cast to the concrete type $@, losing abstraction. | file:///modules/java.base/java/util/List.class:0:0:0:0 | List | List<Integer> | file:///modules/java.base/java/util/ArrayList.class:0:0:0:0 | ArrayList | ArrayList<Integer> |
diff --git a/java/ql/test/kotlin/query-tests/AbstractToConcreteCollection/AbstractToConcreteCollection.qlref b/java/ql/test/kotlin/query-tests/AbstractToConcreteCollection/AbstractToConcreteCollection.qlref
new file mode 100644
index 00000000000..ddc5d95d9d1
--- /dev/null
+++ b/java/ql/test/kotlin/query-tests/AbstractToConcreteCollection/AbstractToConcreteCollection.qlref
@@ -0,0 +1 @@
+Violations of Best Practice/Implementation Hiding/AbstractToConcreteCollection.ql
\ No newline at end of file
diff --git a/java/ql/test/kotlin/query-tests/AbstractToConcreteCollection/Test.kt b/java/ql/test/kotlin/query-tests/AbstractToConcreteCollection/Test.kt
new file mode 100644
index 00000000000..c05317462c4
--- /dev/null
+++ b/java/ql/test/kotlin/query-tests/AbstractToConcreteCollection/Test.kt
@@ -0,0 +1,5 @@
+fun fn(m: MutableList<Int>) {
+    if (m is ArrayList) {
+        m.ensureCapacity(5)
+    }
+}