diff --git a/clang/lib/Serialization/ASTWriterDecl.cpp b/clang/lib/Serialization/ASTWriterDecl.cpp
--- a/clang/lib/Serialization/ASTWriterDecl.cpp
+++ b/clang/lib/Serialization/ASTWriterDecl.cpp
@@ -1089,8 +1089,6 @@
     Record.AddStmt(D->getUninstantiatedDefaultArg());
   Code = serialization::DECL_PARM_VAR;
 
-  assert(!D->isARCPseudoStrong()); // can be true of ImplicitParamDecl
-
   // If the assumptions about the DECL_PARM_VAR abbrev are true, use it.  Here
   // we dynamically check for the properties that we optimize for, but don't
   // know are true of all PARM_VAR_DECLs.