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 9ee45425dc3..463b45d5d6e 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
@@ -2910,6 +2910,7 @@ public class ManagedBuildManager extends AbstractCExtension implements IScannerI
 	}
 
 	public static IManagedBuildInfo getBuildInfoLegacy(IProject project){
+		synchronized(project){
 		IManagedBuildInfo info = null;
 		try {
 			info = getLoaddedBuildInfo(project);
@@ -2927,6 +2928,7 @@ public class ManagedBuildManager extends AbstractCExtension implements IScannerI
 		}
 		
 		return info;
+		}
 	}
 	/**
 	 * Finds, but does not create, the managed build information for the 
diff --git a/build/org.eclipse.cdt.managedbuilder.core/src/org/eclipse/cdt/managedbuilder/internal/macros/MbsMacroSupplier.java b/build/org.eclipse.cdt.managedbuilder.core/src/org/eclipse/cdt/managedbuilder/internal/macros/MbsMacroSupplier.java
index 19b21a944e2..02b0191a5cc 100644
--- a/build/org.eclipse.cdt.managedbuilder.core/src/org/eclipse/cdt/managedbuilder/internal/macros/MbsMacroSupplier.java
+++ b/build/org.eclipse.cdt.managedbuilder.core/src/org/eclipse/cdt/managedbuilder/internal/macros/MbsMacroSupplier.java
@@ -425,7 +425,7 @@ public class MbsMacroSupplier extends BuildCdtVariablesSupplierBase {
 			ITool targetTool = cfg.calculateTargetTool();
 			if(targetTool != null){
 				IOutputType pot = targetTool.getPrimaryOutputType();
-				String prefix = pot.getOutputPrefix();
+				String prefix = pot != null ? pot.getOutputPrefix() : "";	//$NON-NLS-1$
 				
 
 				// Resolve any macros in the outputPrefix
@@ -486,7 +486,7 @@ public class MbsMacroSupplier extends BuildCdtVariablesSupplierBase {
 			ITool targetTool = cfg.calculateTargetTool();
 			if(targetTool != null){
 				IOutputType pot = targetTool.getPrimaryOutputType();
-				String prefix = pot.getOutputPrefix();
+				String prefix = pot != null ? pot.getOutputPrefix() : "";	//$NON-NLS-1$
 				
 				// Resolve any macros in the outputPrefix
 				// Note that we cannot use file macros because if we do a clean