diff --git a/src/s390/simulator-s390.cc b/src/s390/simulator-s390.cc
index f411cc4fe7..dda51e205d 100644
--- a/src/s390/simulator-s390.cc
+++ b/src/s390/simulator-s390.cc
@@ -5682,7 +5682,7 @@ void Simulator::CallInternal(byte* entry, int reg_arg_count) {
 
   // Set up the non-volatile registers with a known value. To be able to check
   // that they are preserved properly across JS execution.
-  intptr_t callee_saved_value = icount_;
+  uintptr_t callee_saved_value = icount_;
   if (reg_arg_count < 5) {
     set_register(r6, callee_saved_value + 6);
   }
@@ -5762,7 +5762,7 @@ intptr_t Simulator::Call(byte* entry, int argument_count, ...) {
   // Remaining arguments passed on stack.
   int64_t original_stack = get_register(sp);
   // Compute position of stack on entry to generated code.
-  intptr_t entry_stack =
+  uintptr_t entry_stack =
       (original_stack -
        (kCalleeRegisterSaveAreaSize + stack_arg_count * sizeof(intptr_t)));
   if (base::OS::ActivationFrameAlignment() != 0) {
@@ -5798,7 +5798,7 @@ intptr_t Simulator::Call(byte* entry, int argument_count, ...) {
 
   // Set up the non-volatile registers with a known value. To be able to check
   // that they are preserved properly across JS execution.
-  intptr_t callee_saved_value = icount_;
+  uintptr_t callee_saved_value = icount_;
   if (reg_arg_count < 5) {
     set_register(r6, callee_saved_value + 6);
   }