diff --git a/build/org.eclipse.cdt.managedbuilder.core/src/org/eclipse/cdt/managedbuilder/internal/core/InputType.java b/build/org.eclipse.cdt.managedbuilder.core/src/org/eclipse/cdt/managedbuilder/internal/core/InputType.java
index d2088edbfc4..ed604f39d27 100644
--- a/build/org.eclipse.cdt.managedbuilder.core/src/org/eclipse/cdt/managedbuilder/internal/core/InputType.java
+++ b/build/org.eclipse.cdt.managedbuilder.core/src/org/eclipse/cdt/managedbuilder/internal/core/InputType.java
@@ -17,6 +17,8 @@ import java.util.List;
 import java.util.StringTokenizer;
 import java.util.Vector;
 
+import org.eclipse.cdt.core.model.ILanguage;
+import org.eclipse.cdt.core.model.LanguageManager;
 import org.eclipse.cdt.core.settings.model.ICStorageElement;
 import org.eclipse.cdt.core.settings.model.util.CDataUtil;
 import org.eclipse.cdt.internal.core.SafeStringInterner;
@@ -1698,6 +1700,15 @@ public class InputType extends BuildObject implements IInputType {
 			langId = getLanguageIdAttribute();
 		}
 
+		if(langId == null){
+			IContentType contentType = getSourceContentType();
+			if (contentType!=null) {
+				ILanguage language = LanguageManager.getInstance().getLanguage(contentType);
+				if (language!=null)
+					langId = language.getId();
+			}
+		}
+
 		return langId;
 	}