diff --git a/loopy/target/c/c_execution.py b/loopy/target/c/c_execution.py
index 6b80bae2076c38485d3590ad579da3e1aa32f998..f7622936c05207c02f8f7065f44b75f3fbff6221 100644
--- a/loopy/target/c/c_execution.py
+++ b/loopy/target/c/c_execution.py
@@ -402,7 +402,7 @@ class CKernelExecutor(KernelExecutorBase):
         if self.kernel.options.write_cl:
             output = all_code
             if self.kernel.options.highlight_cl:
-                output = get_highlighted_code(code=output)
+                output = get_highlighted_code(output)
 
             if self.kernel.options.write_cl is True:
                 print(output)
diff --git a/loopy/transform/iname.py b/loopy/transform/iname.py
index 2b618a464b5103ee28bceded07dc68f9c376c84d..ad1da3e7e67d9d609f51bfed4db7141d14e508dd 100644
--- a/loopy/transform/iname.py
+++ b/loopy/transform/iname.py
@@ -139,8 +139,7 @@ class _InameSplitter(RuleAwareIdentityMapper):
                 and self.split_iname not in expn_state.arg_context
                 and self.within(
                     expn_state.kernel,
-                    expn_state.instruction,
-                    expn_state.stack)):
+                    expn_state.instruction)):
             new_inames = list(expr.inames)
             new_inames.remove(self.split_iname)
             new_inames.extend([self.outer_iname, self.inner_iname])
@@ -157,8 +156,7 @@ class _InameSplitter(RuleAwareIdentityMapper):
                 and self.split_iname not in expn_state.arg_context
                 and self.within(
                     expn_state.kernel,
-                    expn_state.instruction,
-                    expn_state.stack)):
+                    expn_state.instruction)):
             return self.replacement_index
         else:
             return super(_InameSplitter, self).map_variable(expr, expn_state)
@@ -177,6 +175,22 @@ def _split_iname_backend(kernel, split_iname,
         for syntax.
     """
 
+    from loopy.match import parse_match
+    within = parse_match(within)
+
+    # {{{ return the same kernel if no kernel matches
+
+    def _do_not_transform_if_no_within_matches():
+        for insn in kernel.instructions:
+            if within(kernel, insn):
+                return
+
+        return kernel
+
+    _do_not_transform_if_no_within_matches()
+
+    # }}}
+
     existing_tags = kernel.iname_tags(split_iname)
     from loopy.kernel.data import ForceSequentialTag, filter_iname_tags_by_type
     if (do_tagged_check and existing_tags
@@ -230,10 +244,15 @@ def _split_iname_backend(kernel, split_iname,
         name_dim_type, name_idx = space.get_var_dict()[split_iname]
         s = s.intersect(fixed_constraint_set)
 
-        if within is None:
-            s = s.project_out(name_dim_type, name_idx, 1)
+        def _project_out_only_if_all_instructions_in_within():
+            for insn in kernel.instructions:
+                if split_iname in insn.within_inames and (
+                        not within(kernel, insn)):
+                    return s
 
-        return s
+            return s.project_out(name_dim_type, name_idx, 1)
+
+        return _project_out_only_if_all_instructions_in_within()
 
     new_domains = [process_set(dom) for dom in kernel.domains]
 
@@ -249,7 +268,8 @@ def _split_iname_backend(kernel, split_iname,
 
     new_insns = []
     for insn in kernel.instructions:
-        if split_iname in insn.within_inames:
+        if split_iname in insn.within_inames and (
+                within(kernel, insn)):
             new_within_inames = (
                     (insn.within_inames.copy()
                     - frozenset([split_iname]))
@@ -284,9 +304,6 @@ def _split_iname_backend(kernel, split_iname,
             applied_iname_rewrites=applied_iname_rewrites,
             loop_priority=frozenset(new_priorities))
 
-    from loopy.match import parse_stack_match
-    within = parse_stack_match(within)
-
     rule_mapping_context = SubstitutionRuleMappingContext(
             kernel.substitutions, kernel.get_var_name_generator())
     ins = _InameSplitter(rule_mapping_context, within,
@@ -329,7 +346,7 @@ def split_iname(kernel, split_iname, inner_length,
     :arg inner_tag: The iname tag (see :ref:`iname-tags`) to apply to
         *inner_iname*.
     :arg within: a stack match as understood by
-        :func:`loopy.match.parse_stack_match`.
+        :func:`loopy.match.parse_match`.
     """
     def make_new_loop_index(inner, outer):
         return inner + outer*inner_length
diff --git a/test/test_transform.py b/test/test_transform.py
index ed184fb50c099d5fb2a6a0941d2f2c22c3b757bc..394cf668804ed719920e02bc3d20f62971421c2f 100644
--- a/test/test_transform.py
+++ b/test/test_transform.py
@@ -533,6 +533,23 @@ def test_uniquify_instruction_ids():
     assert all(isinstance(id, str) for id in insn_ids)
 
 
+def test_split_iname_only_if_in_within():
+    knl = lp.make_kernel(
+            "{[i]: 0<=i<10}",
+            """
+            c[i] = 3*d[i] {id=to_split}
+            a[i] = 2*b[i] {id=not_to_split}
+            """)
+
+    knl = lp.split_iname(knl, "i", 4, within='id:to_split')
+
+    for insn in knl.instructions:
+        if insn.id == 'to_split':
+            assert insn.within_inames == frozenset({'i_outer', 'i_inner'})
+        if insn.id == 'not_to_split':
+            assert insn.within_inames == frozenset({'i'})
+
+
 if __name__ == "__main__":
     if len(sys.argv) > 1:
         exec(sys.argv[1])