diff --git a/lib/Target/WebAssembly/WebAssemblyPeephole.cpp b/lib/Target/WebAssembly/WebAssemblyPeephole.cpp
index 40b809b949b..1a8afee8818 100644
--- a/lib/Target/WebAssembly/WebAssemblyPeephole.cpp
+++ b/lib/Target/WebAssembly/WebAssemblyPeephole.cpp
@@ -114,21 +114,16 @@ bool WebAssemblyPeephole::runOnMachineFunction(MachineFunction &MF) {
             LibFunc::Func Func;
             if (LibInfo.getLibFunc(Name, Func)) {
               const auto &Op2 = MI.getOperand(2);
-              if (Op2.isReg()) {
-                MachineOperand &MO = MI.getOperand(0);
-                unsigned OldReg = MO.getReg();
-                unsigned NewReg = Op2.getReg();
-                if (MRI.getRegClass(NewReg) != MRI.getRegClass(OldReg))
-                  report_fatal_error("Peephole: call to builtin function with "
-                                     "wrong signature, from/to mismatch");
-                Changed |= MaybeRewriteToDiscard(OldReg, NewReg, MO, MFI, MRI);
-              } else if (Op2.isFI()) {
-                break;
-              } else {
+              if (!Op2.isReg())
                 report_fatal_error("Peephole: call to builtin function with "
-                                   "wrong signature, not consuming reg or "
-                                   "frame index");
-              }
+                                   "wrong signature, not consuming reg");
+              MachineOperand &MO = MI.getOperand(0);
+              unsigned OldReg = MO.getReg();
+              unsigned NewReg = Op2.getReg();
+              if (MRI.getRegClass(NewReg) != MRI.getRegClass(OldReg))
+                report_fatal_error("Peephole: call to builtin function with "
+                                   "wrong signature, from/to mismatch");
+              Changed |= MaybeRewriteToDiscard(OldReg, NewReg, MO, MFI, MRI);
             }
           }
         }