diff --git a/build/org.eclipse.cdt.managedbuilder.core/src/org/eclipse/cdt/managedbuilder/internal/core/Builder.java b/build/org.eclipse.cdt.managedbuilder.core/src/org/eclipse/cdt/managedbuilder/internal/core/Builder.java
index 30e0e4cee26..7a70678a9b5 100644
--- a/build/org.eclipse.cdt.managedbuilder.core/src/org/eclipse/cdt/managedbuilder/internal/core/Builder.java
+++ b/build/org.eclipse.cdt.managedbuilder.core/src/org/eclipse/cdt/managedbuilder/internal/core/Builder.java
@@ -2372,6 +2372,8 @@ public class Builder extends BuildObject implements IBuilder, IMatchKeyProvider
 	
 	void removeErrorParsers(Set set){
 		Set oldSet = contributeErrorParsers(null);
+		if(oldSet == null)
+			oldSet = new HashSet();
 		oldSet.removeAll(set);
 		setErrorParserList((String[])oldSet.toArray(new String[oldSet.size()]));
 	}