diff --git a/js/src/jit/mips/BaselineIC-mips.cpp b/js/src/jit/mips/BaselineIC-mips.cpp
index 777f5a60f796..595a3f9cc7e2 100644
--- a/js/src/jit/mips/BaselineIC-mips.cpp
+++ b/js/src/jit/mips/BaselineIC-mips.cpp
@@ -90,10 +90,12 @@ ICBinaryArith_Int32::Compiler::generateStubCode(MacroAssembler &masm)
       case JSOP_ADD:
         // We know R0.typeReg() already contains the integer tag. No boxing
         // required.
-        masm.ma_addTestOverflow(R0.payloadReg(), R0.payloadReg(), R1.payloadReg(), &failure);
+        masm.ma_addTestOverflow(scratchReg, R0.payloadReg(), R1.payloadReg(), &failure);
+        masm.move32(scratchReg, R0.payloadReg());
         break;
       case JSOP_SUB:
-        masm.ma_subTestOverflow(R0.payloadReg(), R0.payloadReg(), R1.payloadReg(), &failure);
+        masm.ma_subTestOverflow(scratchReg, R0.payloadReg(), R1.payloadReg(), &failure);
+        masm.move32(scratchReg, R0.payloadReg());
         break;
       case JSOP_MUL: {
         masm.ma_mul_branch_overflow(scratchReg, R0.payloadReg(), R1.payloadReg(), &failure);
diff --git a/js/src/jit/mips/MacroAssembler-mips.cpp b/js/src/jit/mips/MacroAssembler-mips.cpp
index fdbab59aa96f..0a5154b815b6 100644
--- a/js/src/jit/mips/MacroAssembler-mips.cpp
+++ b/js/src/jit/mips/MacroAssembler-mips.cpp
@@ -489,17 +489,16 @@ void
 MacroAssemblerMIPS::ma_addTestOverflow(Register rd, Register rs, Register rt, Label *overflow)
 {
     Label goodAddition;
-    as_addu(SecondScratchReg, rs, rt);
+    as_addu(rd, rs, rt);
 
     as_xor(ScratchRegister, rs, rt); // If different sign, no overflow
     ma_b(ScratchRegister, Imm32(0), &goodAddition, Assembler::LessThan, ShortJump);
 
     // If different sign, then overflow
-    as_xor(ScratchRegister, rs, SecondScratchReg);
+    as_xor(ScratchRegister, rs, rd);
     ma_b(ScratchRegister, Imm32(0), overflow, Assembler::LessThan);
 
     bind(&goodAddition);
-    ma_move(rd, SecondScratchReg);
 }
 
 void
@@ -509,18 +508,17 @@ MacroAssemblerMIPS::ma_addTestOverflow(Register rd, Register rs, Imm32 imm, Labe
     // Check for unsigned range because of as_xori
     if (Imm16::isInSignedRange(imm.value) && Imm16::isInUnsignedRange(imm.value)) {
         Label goodAddition;
-        as_addiu(SecondScratchReg, rs, imm.value);
+        as_addiu(rd, rs, imm.value);
 
         // If different sign, no overflow
         as_xori(ScratchRegister, rs, imm.value);
         ma_b(ScratchRegister, Imm32(0), &goodAddition, Assembler::LessThan, ShortJump);
 
         // If different sign, then overflow
-        as_xor(ScratchRegister, rs, SecondScratchReg);
+        as_xor(ScratchRegister, rs, rd);
         ma_b(ScratchRegister, Imm32(0), overflow, Assembler::LessThan);
 
         bind(&goodAddition);
-        ma_move(rd, SecondScratchReg);
     } else {
         ma_li(ScratchRegister, imm);
         ma_addTestOverflow(rd, rs, ScratchRegister, overflow);
@@ -557,17 +555,16 @@ MacroAssemblerMIPS::ma_subTestOverflow(Register rd, Register rs, Register rt, La
     Label goodSubtraction;
     // Use second scratch. The instructions generated by ma_b don't use the
     // second scratch register.
-    ma_subu(SecondScratchReg, rs, rt);
+    ma_subu(rd, rs, rt);
 
     as_xor(ScratchRegister, rs, rt); // If same sign, no overflow
     ma_b(ScratchRegister, Imm32(0), &goodSubtraction, Assembler::GreaterThanOrEqual, ShortJump);
 
     // If different sign, then overflow
-    as_xor(ScratchRegister, rs, SecondScratchReg);
+    as_xor(ScratchRegister, rs, rd);
     ma_b(ScratchRegister, Imm32(0), overflow, Assembler::LessThan);
 
     bind(&goodSubtraction);
-    ma_move(rd, SecondScratchReg);
 }
 
 void