diff --git a/nipype/interfaces/afni/base.py b/nipype/interfaces/afni/base.py
index 20a4a9b4d6..31a9f7585d 100644
--- a/nipype/interfaces/afni/base.py
+++ b/nipype/interfaces/afni/base.py
@@ -98,7 +98,7 @@ def standard_image(img_name):
             resource_monitor=False,
             terminal_output="allatonce",
         ).run()
-        if clout.runtime.returncode is not 0:
+        if clout.runtime.returncode != 0:
             return None
 
         out = clout.runtime.stdout
diff --git a/nipype/interfaces/diffusion_toolkit/base.py b/nipype/interfaces/diffusion_toolkit/base.py
index b4b5ba1893..2068f18988 100644
--- a/nipype/interfaces/diffusion_toolkit/base.py
+++ b/nipype/interfaces/diffusion_toolkit/base.py
@@ -47,7 +47,7 @@ def version():
         """
         clout = CommandLine(command="dti_recon", terminal_output="allatonce").run()
 
-        if clout.runtime.returncode is not 0:
+        if clout.runtime.returncode != 0:
             return None
 
         dtirecon = clout.runtime.stdout
diff --git a/nipype/utils/tests/test_filemanip.py b/nipype/utils/tests/test_filemanip.py
index e8da256261..299029a8d2 100644
--- a/nipype/utils/tests/test_filemanip.py
+++ b/nipype/utils/tests/test_filemanip.py
@@ -154,7 +154,7 @@ def test_copyfiles(_temp_analyze_files, _temp_analyze_files_prime):
 
 
 def test_linkchain(_temp_analyze_files):
-    if os.name is not "posix":
+    if os.name != "posix":
         return
     orig_img, orig_hdr = _temp_analyze_files
     pth, fname = os.path.split(orig_img)
@@ -230,7 +230,7 @@ def test_recopy(_temp_analyze_files):
 
 
 def test_copyfallback(_temp_analyze_files):
-    if os.name is not "posix":
+    if os.name != "posix":
         return
     orig_img, orig_hdr = _temp_analyze_files
     pth, imgname = os.path.split(orig_img)