diff --git a/build/org.eclipse.cdt.managedbuilder.core/src/org/eclipse/cdt/managedbuilder/core/ManagedBuildManager.java b/build/org.eclipse.cdt.managedbuilder.core/src/org/eclipse/cdt/managedbuilder/core/ManagedBuildManager.java
index c9547375f4f..aead8e06549 100644
--- a/build/org.eclipse.cdt.managedbuilder.core/src/org/eclipse/cdt/managedbuilder/core/ManagedBuildManager.java
+++ b/build/org.eclipse.cdt.managedbuilder.core/src/org/eclipse/cdt/managedbuilder/core/ManagedBuildManager.java
@@ -1753,6 +1753,9 @@ public class ManagedBuildManager extends AbstractCExtension implements IScannerI
 	 * call this method first, it is effectively a startup method
 	 */
 	private static void loadExtensions() throws BuildException {
+		if (projectTypesLoaded)
+			return;
+
 		loadExtensionsSynchronized();
 	}