diff --git a/lib/CodeGen/PrologEpilogInserter.cpp b/lib/CodeGen/PrologEpilogInserter.cpp
index b3bf88d6893..aabf78bd338 100644
--- a/lib/CodeGen/PrologEpilogInserter.cpp
+++ b/lib/CodeGen/PrologEpilogInserter.cpp
@@ -321,7 +321,8 @@ void PEI::calculateFrameObjectOffsets(MachineFunction &Fn) {
 
   // Remember the required stack alignment in case targets need it to perform
   // dynamic stack alignment.
-  FFI->setMaxAlignment(MaxAlign);
+  assert(FFI->getMaxAlignment() == MaxAlign &&
+         "Stack alignment calculation broken!");
 }