diff --git a/build/org.eclipse.cdt.managedbuilder.core/src/org/eclipse/cdt/managedbuilder/language/settings/providers/AbstractBuiltinSpecsDetector.java b/build/org.eclipse.cdt.managedbuilder.core/src/org/eclipse/cdt/managedbuilder/language/settings/providers/AbstractBuiltinSpecsDetector.java
index 44ea02f5fd5..2287de07a38 100644
--- a/build/org.eclipse.cdt.managedbuilder.core/src/org/eclipse/cdt/managedbuilder/language/settings/providers/AbstractBuiltinSpecsDetector.java
+++ b/build/org.eclipse.cdt.managedbuilder.core/src/org/eclipse/cdt/managedbuilder/language/settings/providers/AbstractBuiltinSpecsDetector.java
@@ -872,6 +872,7 @@ public abstract class AbstractBuiltinSpecsDetector extends AbstractLanguageSetti
 		clone.envMngr = null;
 		clone.environmentMap = null;
 		clone.envPathHash = HASH_NOT_INITIALIZED;
+		this.properties.remove(ATTR_ENV_HASH);
 		return clone;
 	}