diff --git a/src/builtins/s390/builtins-s390.cc b/src/builtins/s390/builtins-s390.cc
index 198ba0971d..f60a02d7f3 100644
--- a/src/builtins/s390/builtins-s390.cc
+++ b/src/builtins/s390/builtins-s390.cc
@@ -2274,9 +2274,10 @@ void Builtins::Generate_ArgumentsAdaptorTrampoline(MacroAssembler* masm) {
 }
 
 void Builtins::Generate_WasmCompileLazy(MacroAssembler* masm) {
-  // The function index was put in r7 by the jump table trampoline.
+  // The function index was put in a register by the jump table trampoline.
   // Convert to Smi for the runtime call.
-  __ SmiTag(r7, r7);
+  __ SmiTag(kWasmLazyCompileFuncIndexRegister,
+            kWasmLazyCompileFuncIndexRegister);
   {
     HardAbortScope hard_abort(masm);  // Avoid calls to Abort.
     FrameAndConstantPoolScope scope(masm, StackFrame::WASM_COMPILE_LAZY);
diff --git a/src/s390/macro-assembler-s390.h b/src/s390/macro-assembler-s390.h
index 98f8bb6e03..62179f7db6 100644
--- a/src/s390/macro-assembler-s390.h
+++ b/src/s390/macro-assembler-s390.h
@@ -38,6 +38,7 @@ constexpr Register kRuntimeCallFunctionRegister = r3;
 constexpr Register kRuntimeCallArgCountRegister = r2;
 constexpr Register kRuntimeCallArgvRegister = r4;
 constexpr Register kWasmInstanceRegister = r6;
+constexpr Register kWasmCompileLazyFuncIndexRegister = r7;
 
 // ----------------------------------------------------------------------------
 // Static helper functions
diff --git a/src/wasm/jump-table-assembler.cc b/src/wasm/jump-table-assembler.cc
index 9e64f1679c..bf048f8fd3 100644
--- a/src/wasm/jump-table-assembler.cc
+++ b/src/wasm/jump-table-assembler.cc
@@ -122,7 +122,7 @@ void JumpTableAssembler::NopBytes(int bytes) {
 void JumpTableAssembler::EmitLazyCompileJumpSlot(uint32_t func_index,
                                                  Address lazy_compile_target) {
   // Load function index to r7. 6 bytes
-  lgfi(r7, Operand(func_index));
+  lgfi(kWasmCompileLazyFuncIndexRegister, Operand(func_index));
   // Jump to {lazy_compile_target}. 6 bytes or 12 bytes
   mov(r1, Operand(lazy_compile_target));
   b(r1);  // 2 bytes