diff --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp
index 3b5ab839c6cf7..be8f1fe02e721 100644
--- a/clang/lib/AST/ExprConstant.cpp
+++ b/clang/lib/AST/ExprConstant.cpp
@@ -1961,7 +1961,7 @@ APValue &
 CallStackFrame::createConstexprUnknownAPValues(const VarDecl *Key,
                                                APValue::LValueBase Base) {
   APValue &Result = ConstexprUnknownAPValues[MapKeyTy(Key, Base.getVersion())];
-  Result = APValue(Base, CharUnits::One(), APValue::ConstexprUnknown{});
+  Result = APValue(Base, CharUnits::Zero(), APValue::ConstexprUnknown{});
 
   return Result;
 }