Index: COFF/SymbolTable.cpp
===================================================================
--- COFF/SymbolTable.cpp
+++ COFF/SymbolTable.cpp
@@ -331,7 +331,7 @@
     StringRef name = undef->getName();
     if (name.startswith("__imp_")) {
       Symbol *imp = find(name.substr(strlen("__imp_")));
-      if (imp && isa<Defined>(imp))
+      if (dyn_cast_or_null<Defined>(imp))
         continue;
     }
     if (name.contains("_PchSym_"))