--- a/js/src/jit/MIR.cpp
+++ b/js/src/jit/MIR.cpp
@@ -5084,17 +5084,17 @@ MLoadSlot::printOpcode(GenericPrinter& o
     MDefinition::printOpcode(out);
     out.printf(" %d", slot());
 }
 
 void
 MStoreSlot::printOpcode(GenericPrinter& out) const
 {
     PrintOpcodeName(out, op());
-    out.printf(" ", slot());
+    out.printf(" ");
     getOperand(0)->printName(out);
     out.printf(" %d ", slot());
     getOperand(1)->printName(out);
 }
 
 MDefinition*
 MFunctionEnvironment::foldsTo(TempAllocator& alloc)
 {