diff --git a/runtime/vm/compiler/assembler/assembler_ia32_test.cc b/runtime/vm/compiler/assembler/assembler_ia32_test.cc
index 27dd5637507..8c97ffe629f 100644
--- a/runtime/vm/compiler/assembler/assembler_ia32_test.cc
+++ b/runtime/vm/compiler/assembler/assembler_ia32_test.cc
@@ -5092,7 +5092,8 @@ void CheckIsIdentity(Expect& expect, AssemblerTest* test) {
   }
 }
 
-static const Register kRegRegImmTempReg = EBX;
+// Use a volatile register so we don't have to save it.
+static const Register kRegRegImmTempReg = ECX;
 
 void CheckMovesInputToReturnOnly(Expect& expect,
                                  AssemblerTest* test,