diff --git a/mypyc/ir/rtypes.py b/mypyc/ir/rtypes.py
index 2490da6fe51f..39dce61c2c76 100644
--- a/mypyc/ir/rtypes.py
+++ b/mypyc/ir/rtypes.py
@@ -276,10 +276,12 @@ def __hash__(self) -> int:
 
 if IS_32_BIT_PLATFORM:
     c_size_t_rprimitive = uint32_rprimitive
-    c_pyssize_t_rprimitive = int32_rprimitive
+    c_pyssize_t_rprimitive = RPrimitive('native_int', is_unboxed=True, is_refcounted=False,
+                              ctype='int32_t', size=4)
 else:
     c_size_t_rprimitive = uint64_rprimitive
-    c_pyssize_t_rprimitive = int64_rprimitive
+    c_pyssize_t_rprimitive = RPrimitive('native_int', is_unboxed=True, is_refcounted=False,
+                              ctype='int64_t', size=8)
 
 # Low level pointer, represented as integer in C backends
 pointer_rprimitive = RPrimitive('ptr', is_unboxed=True, is_refcounted=False,
@@ -338,11 +340,13 @@ def is_short_int_rprimitive(rtype: RType) -> bool:
 
 
 def is_int32_rprimitive(rtype: RType) -> bool:
-    return rtype is int32_rprimitive
+    return (rtype is int32_rprimitive or
+            (rtype is c_pyssize_t_rprimitive and rtype._ctype == 'int32_t'))
 
 
 def is_int64_rprimitive(rtype: RType) -> bool:
-    return rtype is int64_rprimitive
+    return (rtype is int64_rprimitive or
+            (rtype is c_pyssize_t_rprimitive and rtype._ctype == 'int64_t'))
 
 
 def is_uint32_rprimitive(rtype: RType) -> bool:
diff --git a/mypyc/test/test_analysis.py b/mypyc/test/test_analysis.py
index e9088d7c1138..82317ef34765 100644
--- a/mypyc/test/test_analysis.py
+++ b/mypyc/test/test_analysis.py
@@ -15,7 +15,7 @@
 from mypyc.ir.func_ir import all_values
 from mypyc.test.testutil import (
     ICODE_GEN_BUILTINS, use_custom_builtins, MypycDataSuite, build_ir_for_single_file,
-    assert_test_output, replace_native_int
+    assert_test_output
 )
 
 files = [
@@ -32,7 +32,6 @@ def run_case(self, testcase: DataDrivenTestCase) -> None:
         """Perform a data-flow analysis test case."""
 
         with use_custom_builtins(os.path.join(self.data_prefix, ICODE_GEN_BUILTINS), testcase):
-            testcase.output = replace_native_int(testcase.output)
             try:
                 ir = build_ir_for_single_file(testcase.input)
             except CompileError as e:
diff --git a/mypyc/test/test_exceptions.py b/mypyc/test/test_exceptions.py
index a313e794bab6..67df5ce5c38a 100644
--- a/mypyc/test/test_exceptions.py
+++ b/mypyc/test/test_exceptions.py
@@ -16,7 +16,7 @@
 from mypyc.transform.refcount import insert_ref_count_opcodes
 from mypyc.test.testutil import (
     ICODE_GEN_BUILTINS, use_custom_builtins, MypycDataSuite, build_ir_for_single_file,
-    assert_test_output, remove_comment_lines, replace_native_int
+    assert_test_output, remove_comment_lines
 )
 
 files = [
@@ -32,7 +32,6 @@ def run_case(self, testcase: DataDrivenTestCase) -> None:
         """Perform a runtime checking transformation test case."""
         with use_custom_builtins(os.path.join(self.data_prefix, ICODE_GEN_BUILTINS), testcase):
             expected_output = remove_comment_lines(testcase.output)
-            expected_output = replace_native_int(expected_output)
             try:
                 ir = build_ir_for_single_file(testcase.input)
             except CompileError as e:
diff --git a/mypyc/test/test_irbuild.py b/mypyc/test/test_irbuild.py
index 32f0e758c91c..8c7b03f8bc39 100644
--- a/mypyc/test/test_irbuild.py
+++ b/mypyc/test/test_irbuild.py
@@ -10,7 +10,7 @@
 from mypyc.ir.pprint import format_func
 from mypyc.test.testutil import (
     ICODE_GEN_BUILTINS, use_custom_builtins, MypycDataSuite, build_ir_for_single_file,
-    assert_test_output, remove_comment_lines, replace_native_int, replace_word_size,
+    assert_test_output, remove_comment_lines, replace_word_size,
     infer_ir_build_options_from_test_name
 )
 
@@ -50,7 +50,6 @@ def run_case(self, testcase: DataDrivenTestCase) -> None:
             return
         with use_custom_builtins(os.path.join(self.data_prefix, ICODE_GEN_BUILTINS), testcase):
             expected_output = remove_comment_lines(testcase.output)
-            expected_output = replace_native_int(expected_output)
             expected_output = replace_word_size(expected_output)
             name = testcase.name
             try:
diff --git a/mypyc/test/test_refcount.py b/mypyc/test/test_refcount.py
index 9e96d31e224a..2c9502330cd5 100644
--- a/mypyc/test/test_refcount.py
+++ b/mypyc/test/test_refcount.py
@@ -16,7 +16,7 @@
 from mypyc.transform.uninit import insert_uninit_checks
 from mypyc.test.testutil import (
     ICODE_GEN_BUILTINS, use_custom_builtins, MypycDataSuite, build_ir_for_single_file,
-    assert_test_output, remove_comment_lines, replace_native_int, replace_word_size,
+    assert_test_output, remove_comment_lines, replace_word_size,
     infer_ir_build_options_from_test_name
 )
 
@@ -38,7 +38,6 @@ def run_case(self, testcase: DataDrivenTestCase) -> None:
             return
         with use_custom_builtins(os.path.join(self.data_prefix, ICODE_GEN_BUILTINS), testcase):
             expected_output = remove_comment_lines(testcase.output)
-            expected_output = replace_native_int(expected_output)
             expected_output = replace_word_size(expected_output)
             try:
                 ir = build_ir_for_single_file(testcase.input, options)
diff --git a/mypyc/test/testutil.py b/mypyc/test/testutil.py
index 0c64a35fd052..7ef1f941aa41 100644
--- a/mypyc/test/testutil.py
+++ b/mypyc/test/testutil.py
@@ -215,12 +215,6 @@ def fudge_dir_mtimes(dir: str, delta: int) -> None:
             os.utime(path, times=(new_mtime, new_mtime))
 
 
-def replace_native_int(text: List[str]) -> List[str]:
-    """Replace native_int with platform specific ints"""
-    int_format_str = 'int32' if IS_32_BIT_PLATFORM else 'int64'
-    return [s.replace('native_int', int_format_str) for s in text]
-
-
 def replace_word_size(text: List[str]) -> List[str]:
     """Replace WORDSIZE with platform specific word sizes"""
     result = []