diff --git a/src/main/java/com/google/devtools/build/lib/analysis/test/TestRunnerAction.java b/src/main/java/com/google/devtools/build/lib/analysis/test/TestRunnerAction.java
index 2e8adcc1380803..12e71510e735fa 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/test/TestRunnerAction.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/test/TestRunnerAction.java
@@ -423,6 +423,12 @@ public ImmutableList<Pair<String, Path>> getTestOutputsMapping(
     return builder.build();
   }
 
+  // Test actions are always distinguished by their target name, which must be unique.
+  @Override
+  public final boolean isShareable() {
+    return false;
+  }
+
   @Override
   protected void computeKey(
       ActionKeyContext actionKeyContext,