diff --git a/src/main/java/com/google/devtools/build/lib/packages/RuleClass.java b/src/main/java/com/google/devtools/build/lib/packages/RuleClass.java
index ae0c358..f979d8b 100644
--- a/src/main/java/com/google/devtools/build/lib/packages/RuleClass.java
+++ b/src/main/java/com/google/devtools/build/lib/packages/RuleClass.java
@@ -545,6 +545,8 @@
             parent.getConfigurationFragmentPolicy().getMissingFragmentPolicy());
         supportsConstraintChecking = parent.supportsConstraintChecking;
 
+        addRequiredToolchains(parent.getRequiredToolchains());
+
         for (Attribute attribute : parent.getAttributes()) {
           String attrName = attribute.getName();
           Preconditions.checkArgument(