diff --git a/js/src/methodjit/Compiler.cpp b/js/src/methodjit/Compiler.cpp
index 9dd6e697db2..d788afdc87a 100644
--- a/js/src/methodjit/Compiler.cpp
+++ b/js/src/methodjit/Compiler.cpp
@@ -5449,13 +5449,11 @@ mjit::Compiler::jsop_setprop(JSAtom *atom, bool usePropCache, bool popGuaranteed
 #ifdef JSGC_INCREMENTAL_MJ
             /* Write barrier. */
             if (cx->compartment->needsBarrier()) {
-                frame.pinReg(address.base);
                 stubcc.linkExit(masm.jump(), Uses(0));
                 stubcc.leave();
                 stubcc.masm.addPtr(Imm32(address.offset), address.base, Registers::ArgReg1);
                 OOL_STUBCALL(stubs::WriteBarrier, REJOIN_NONE);
                 stubcc.rejoin(Changes(0));
-                frame.unpinReg(address.base);
             }
 #endif
 
@@ -5492,9 +5490,9 @@ mjit::Compiler::jsop_setprop(JSAtom *atom, bool usePropCache, bool popGuaranteed
             if (!isObject)
                 notObject = frame.testObject(Assembler::NotEqual, lhs);
 #ifdef JSGC_INCREMENTAL_MJ
+            frame.pinReg(reg);
             if (cx->compartment->needsBarrier() && propertyTypes->needsBarrier(cx)) {
                 /* Write barrier. */
-                frame.pinReg(reg);
                 Jump j = masm.testGCThing(Address(reg, JSObject::getFixedSlotOffset(slot)));
                 stubcc.linkExit(j, Uses(0));
                 stubcc.leave();
@@ -5502,8 +5500,8 @@ mjit::Compiler::jsop_setprop(JSAtom *atom, bool usePropCache, bool popGuaranteed
                                    reg, Registers::ArgReg1);
                 OOL_STUBCALL(stubs::GCThingWriteBarrier, REJOIN_NONE);
                 stubcc.rejoin(Changes(0));
-                frame.unpinReg(reg);
             }
+            frame.unpinReg(reg);
 #endif
             if (!isObject) {
                 stubcc.linkExit(notObject.get(), Uses(2));
diff --git a/js/src/methodjit/FastOps.cpp b/js/src/methodjit/FastOps.cpp
index 3a319cc16d2..d79084cb377 100644
--- a/js/src/methodjit/FastOps.cpp
+++ b/js/src/methodjit/FastOps.cpp
@@ -1172,19 +1172,17 @@ mjit::Compiler::jsop_setelem_dense()
 
         /*
          * The sync call below can potentially clobber key.reg() and slotsReg.
-         * We pin them to avoid this. Additionally, the WriteBarrier stub can
+         * So we save and restore them. Additionally, the WriteBarrier stub can
          * clobber both registers. The rejoin call will restore key.reg() but
-         * not slotsReg. So we save slotsReg in the frame and restore it after
-         * the stub call.
+         * not slotsReg. So we restore it again after the stub call.
          */
         stubcc.masm.storePtr(slotsReg, FrameAddress(offsetof(VMFrame, scratch)));
-        frame.pinReg(slotsReg);
         if (!key.isConstant())
-            frame.pinReg(key.reg());
+            stubcc.masm.push(key.reg());
         frame.sync(stubcc.masm, Uses(3));
         if (!key.isConstant())
-            frame.unpinReg(key.reg());
-        frame.unpinReg(slotsReg);
+            stubcc.masm.pop(key.reg());
+        stubcc.masm.loadPtr(FrameAddress(offsetof(VMFrame, scratch)), slotsReg);
 
         if (key.isConstant())
             stubcc.masm.lea(Address(slotsReg, key.index() * sizeof(Value)), Registers::ArgReg1);