diff --git a/lib/AST/DeclCXX.cpp b/lib/AST/DeclCXX.cpp
index 73cba1d..aa4b2dd 100644
--- a/lib/AST/DeclCXX.cpp
+++ b/lib/AST/DeclCXX.cpp
@@ -94,9 +94,7 @@
     // Keep track of inherited vbases for this base class.
     const CXXBaseSpecifier *Base = Bases[i];
     QualType BaseType = Base->getType();
-    // Skip template types.
-    // FIXME. This means that this list must be rebuilt during template
-    // instantiation.
+    // Skip dependent types; we can't do any checking on them now.
     if (BaseType->isDependentType())
       continue;
     CXXRecordDecl *BaseClassDecl
@@ -143,6 +141,9 @@
     data().NumVBases = vbaseCount;
     for (int i = 0; i < vbaseCount; i++) {
       QualType QT = UniqueVbases[i]->getType();
+      // Skip dependent types; we can't do any checking on them now.
+      if (QT->isDependentType())
+        continue;
       CXXRecordDecl *VBaseClassDecl
         = cast<CXXRecordDecl>(QT->getAs<RecordType>()->getDecl());
       data().VBases[i] =
diff --git a/lib/Sema/SemaDeclCXX.cpp b/lib/Sema/SemaDeclCXX.cpp
index e12a104..20a8303 100644
--- a/lib/Sema/SemaDeclCXX.cpp
+++ b/lib/Sema/SemaDeclCXX.cpp
@@ -586,7 +586,10 @@
     return true;
 
   AdjustDeclIfTemplate(classdecl);
-  CXXRecordDecl *Class = cast<CXXRecordDecl>(classdecl.getAs<Decl>());
+  CXXRecordDecl *Class = dyn_cast<CXXRecordDecl>(classdecl.getAs<Decl>());
+  if (!Class)
+    return true;
+
   QualType BaseType = GetTypeFromParser(basetype);
   if (CXXBaseSpecifier *BaseSpec = CheckBaseSpecifier(Class, SpecifierRange,
                                                       Virtual, Access,
diff --git a/test/SemaTemplate/dependent-base-classes.cpp b/test/SemaTemplate/dependent-base-classes.cpp
index cd90f63..3b795c9 100644
--- a/test/SemaTemplate/dependent-base-classes.cpp
+++ b/test/SemaTemplate/dependent-base-classes.cpp
@@ -109,3 +109,15 @@
     }
   };
 }
+
+namespace PR6413 {
+  template <typename T> class Base_A { };
+  
+  class Base_B { };
+  
+  template <typename T>
+  class Derived
+    : public virtual Base_A<T>
+    , public virtual Base_B
+  { };
+}