diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyRegStackify.cpp b/llvm/lib/Target/WebAssembly/WebAssemblyRegStackify.cpp
index ac016a7b9b0a..9fbde70634ac 100644
--- a/llvm/lib/Target/WebAssembly/WebAssemblyRegStackify.cpp
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyRegStackify.cpp
@@ -127,6 +127,8 @@ bool WebAssemblyRegStackify::runOnMachineFunction(MachineFunction &MF) {
   WebAssemblyFunctionInfo &MFI = *MF.getInfo<WebAssemblyFunctionInfo>();
   AliasAnalysis &AA = getAnalysis<AAResultsWrapperPass>().getAAResults();
 
+  assert(MRI.isSSA() && "RegStackify depends on SSA form");
+
   // Walk the instructions from the bottom up. Currently we don't look past
   // block boundaries, and the blocks aren't ordered so the block visitation
   // order isn't significant, but we may want to change this in the future.
diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyStoreResults.cpp b/llvm/lib/Target/WebAssembly/WebAssemblyStoreResults.cpp
index b67453bee708..21122ba2b2ea 100644
--- a/llvm/lib/Target/WebAssembly/WebAssemblyStoreResults.cpp
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyStoreResults.cpp
@@ -72,6 +72,8 @@ bool WebAssemblyStoreResults::runOnMachineFunction(MachineFunction &MF) {
   const MachineRegisterInfo &MRI = MF.getRegInfo();
   MachineDominatorTree &MDT = getAnalysis<MachineDominatorTree>();
 
+  assert(MRI.isSSA() && "StoreResults depends on SSA form");
+
   for (auto &MBB : MF) {
     DEBUG(dbgs() << "Basic Block: " << MBB.getName() << '\n');
     for (auto &MI : MBB)