diff --git a/library/_builtins.py b/library/_builtins.py
index 25b5ed3b2..049dcf2d1 100644
--- a/library/_builtins.py
+++ b/library/_builtins.py
@@ -1002,6 +1002,7 @@ def _slice_start_long(start, step, length):
 
 
 def _slice_step(step):
+    "$intrinsic$"
     _builtin()
 
 
diff --git a/runtime/under-builtins-module.cpp b/runtime/under-builtins-module.cpp
index 85d2de346..26c55cc96 100644
--- a/runtime/under-builtins-module.cpp
+++ b/runtime/under-builtins-module.cpp
@@ -4570,6 +4570,21 @@ RawObject FUNC(_builtins, _slice_start_long)(Thread* thread, Arguments args) {
   return *start;
 }
 
+bool FUNC(_builtins, _slice_step_intrinsic)(Thread* thread) {
+  RawObject step_obj = thread->stackTop();
+  if (step_obj.isNoneType()) {
+    thread->stackPop();
+    thread->stackSetTop(SmallInt::fromWord(1));
+    return true;
+  }
+  if (step_obj.isSmallInt()) {
+    thread->stackPop();
+    thread->stackSetTop(step_obj);
+    return true;
+  }
+  return false;
+}
+
 RawObject FUNC(_builtins, _slice_step)(Thread* thread, Arguments args) {
   RawObject step_obj = args.get(0);
   if (step_obj.isNoneType()) return SmallInt::fromWord(1);