diff --git a/java/ql/src/semmle/code/java/dataflow/internal/TaintTrackingUtil.qll b/java/ql/src/semmle/code/java/dataflow/internal/TaintTrackingUtil.qll
index 93b8641d11b..966daea783f 100644
--- a/java/ql/src/semmle/code/java/dataflow/internal/TaintTrackingUtil.qll
+++ b/java/ql/src/semmle/code/java/dataflow/internal/TaintTrackingUtil.qll
@@ -69,6 +69,7 @@ private module Cached {
     |
       f instanceof ArrayContent or
       f instanceof CollectionContent or
+      f instanceof MapKeyContent or
       f instanceof MapValueContent
     )
     or