diff --git a/js/src/jit/arm64/MacroAssembler-arm64-inl.h b/js/src/jit/arm64/MacroAssembler-arm64-inl.h
index a0cdc35b1633..8b98bf50df1d 100644
--- a/js/src/jit/arm64/MacroAssembler-arm64-inl.h
+++ b/js/src/jit/arm64/MacroAssembler-arm64-inl.h
@@ -1598,7 +1598,7 @@ void MacroAssembler::branchMulPtr(Condition cond, Register src, Register dest,
 
 void MacroAssembler::branchNegPtr(Condition cond, Register reg, Label* label) {
   MOZ_ASSERT(cond == Overflow);
-  negPtr(reg);
+  negs64(reg);
   B(label, cond);
 }
 
diff --git a/js/src/jit/arm64/MacroAssembler-arm64.h b/js/src/jit/arm64/MacroAssembler-arm64.h
index 1add0d09656e..f137b970bd7f 100644
--- a/js/src/jit/arm64/MacroAssembler-arm64.h
+++ b/js/src/jit/arm64/MacroAssembler-arm64.h
@@ -1300,6 +1300,9 @@ class MacroAssemblerCompat : public vixl::MacroAssembler {
   void negs32(Register reg) {
     Negs(ARMRegister(reg, 32), Operand(ARMRegister(reg, 32)));
   }
+  void negs64(Register reg) {
+    Negs(ARMRegister(reg, 64), Operand(ARMRegister(reg, 64)));
+  }
 
   void ret() {
     pop(lr);