diff --git a/src/Generator/Passes/Pass.cs b/src/Generator/Passes/Pass.cs
index d9bb6efe..d5d84404 100644
--- a/src/Generator/Passes/Pass.cs
+++ b/src/Generator/Passes/Pass.cs
@@ -30,6 +30,9 @@ namespace CppSharp.Passes
 
         public virtual bool VisitTranslationUnit(TranslationUnit unit)
         {
+            if (!unit.IsValid)
+                return false;
+
             if (unit.IsSystemHeader)
                 return false;