diff --git a/build/org.eclipse.cdt.build.gcc.core/src/org/eclipse/cdt/build/gcc/core/internal/GCCPathToolChainProvider.java b/build/org.eclipse.cdt.build.gcc.core/src/org/eclipse/cdt/build/gcc/core/internal/GCCPathToolChainProvider.java
index cc2d84069a6..dae4f2df0d5 100644
--- a/build/org.eclipse.cdt.build.gcc.core/src/org/eclipse/cdt/build/gcc/core/internal/GCCPathToolChainProvider.java
+++ b/build/org.eclipse.cdt.build.gcc.core/src/org/eclipse/cdt/build/gcc/core/internal/GCCPathToolChainProvider.java
@@ -15,9 +15,11 @@ import java.util.regex.Pattern;
 import org.eclipse.cdt.build.gcc.core.ClangToolChain;
 import org.eclipse.cdt.build.gcc.core.GCCToolChain;
 import org.eclipse.cdt.build.gcc.core.GCCToolChain.GCCInfo;
+import org.eclipse.cdt.core.CCorePlugin;
 import org.eclipse.cdt.core.build.IToolChain;
 import org.eclipse.cdt.core.build.IToolChainManager;
 import org.eclipse.cdt.core.build.IToolChainProvider;
+import org.eclipse.core.runtime.CoreException;
 import org.eclipse.core.runtime.Platform;
 
 /**
@@ -66,7 +68,14 @@ public class GCCPathToolChainProvider implements IToolChainProvider {
 										gcc.setProperty(IToolChain.ATTR_OS, Platform.OS_MACOSX);
 										break;
 									}
-									manager.addToolChain(gcc);
+									try {
+										if (manager.getToolChain(gcc.getTypeId(), gcc.getId()) == null) {
+											// Only add if another provider hasn't already added it
+											manager.addToolChain(gcc);
+										}
+									} catch (CoreException e) {
+										CCorePlugin.log(e.getStatus());
+									}
 								}
 							}
 						} catch (IOException e) {
diff --git a/core/org.eclipse.cdt.core/src/org/eclipse/cdt/core/build/CBuildConfiguration.java b/core/org.eclipse.cdt.core/src/org/eclipse/cdt/core/build/CBuildConfiguration.java
index 92f5f8eb695..8bd5cc76e6b 100644
--- a/core/org.eclipse.cdt.core/src/org/eclipse/cdt/core/build/CBuildConfiguration.java
+++ b/core/org.eclipse.cdt.core/src/org/eclipse/cdt/core/build/CBuildConfiguration.java
@@ -149,7 +149,9 @@ public abstract class CBuildConfiguration extends PlatformObject
 		Preferences settings = getSettings();
 		settings.put(TOOLCHAIN_TYPE, toolChain.getTypeId());
 		settings.put(TOOLCHAIN_ID, toolChain.getId());
-		settings.put(LAUNCH_MODE, launchMode);
+		if (launchMode != null) {
+			settings.put(LAUNCH_MODE, launchMode);
+		}
 		try {
 			settings.flush();
 		} catch (BackingStoreException e) {