diff --git a/src/maglev/maglev-ir.cc b/src/maglev/maglev-ir.cc
index d574c5de11..74c682ba3f 100644
--- a/src/maglev/maglev-ir.cc
+++ b/src/maglev/maglev-ir.cc
@@ -1958,7 +1958,7 @@ void StringAt::GenerateCode(MaglevAssembler* masm,
 
   __ bind(&sliced_string);
   {
-    Register offset = rcx;
+    Register offset = scratch1;
     __ movl(offset, FieldOperand(string_object, SlicedString::kOffsetOffset));
     __ SmiUntag(offset);
     __ DecompressAnyTagged(