diff --git a/share/qtcreator/debugger/dumper.py b/share/qtcreator/debugger/dumper.py
index d44c528778a..2c66f39a5d1 100644
--- a/share/qtcreator/debugger/dumper.py
+++ b/share/qtcreator/debugger/dumper.py
@@ -1078,7 +1078,7 @@ class DumperBase:
 
         reslist = []
         for item in res.get('variables', {}):
-            if not 'iname' in item:
+            if 'iname' not in item:
                 item['iname'] = '.' + item.get('name')
             reslist.append(self.variablesToMi(item, 'local'))
 
diff --git a/share/qtcreator/debugger/lldbbridge.py b/share/qtcreator/debugger/lldbbridge.py
index cf19c1eac83..0c53a1c26f3 100644
--- a/share/qtcreator/debugger/lldbbridge.py
+++ b/share/qtcreator/debugger/lldbbridge.py
@@ -2216,7 +2216,7 @@ class SyntheticChildrenProvider(SummaryProvider):
         SummaryProvider.update(self)
 
         self.synthetic_children = []
-        if not 'children' in self.summary:
+        if 'children' not in self.summary:
             return
 
         dereference_child = None
diff --git a/tests/system/shared/debugger.py b/tests/system/shared/debugger.py
index 28c5398f66f..77632241f3b 100644
--- a/tests/system/shared/debugger.py
+++ b/tests/system/shared/debugger.py
@@ -255,7 +255,7 @@ def verifyBreakPoint(bpToVerify):
 def __isWinFirewallRunning__():
     if hasattr(__isWinFirewallRunning__, "fireWallState"):
         return __isWinFirewallRunning__.fireWallState
-    if not platform.system() in ('Microsoft' 'Windows'):
+    if platform.system() not in ('Microsoft' 'Windows'):
         __isWinFirewallRunning__.fireWallState = False
         return False
     result = getOutputFromCmdline(["netsh", "firewall", "show", "state"])
diff --git a/tests/system/shared/qtcreator.py b/tests/system/shared/qtcreator.py
index 4b909c6e441..c5fa6792b03 100644
--- a/tests/system/shared/qtcreator.py
+++ b/tests/system/shared/qtcreator.py
@@ -292,7 +292,7 @@ def copySettingsToTmpDir(destination=None, omitFiles=[]):
             if not os.path.exists(folder):
                 os.makedirs(folder)
         for ff in f:
-            if not ff in omitFiles:
+            if ff not in omitFiles:
                 shutil.copy(os.path.join(r, ff), currentPath)
     if platform.system() in ('Linux', 'Darwin'):
         substituteTildeWithinToolchains(tmpSettingsDir)
diff --git a/tests/system/suite_general/tst_create_proj_wizard/test.py b/tests/system/suite_general/tst_create_proj_wizard/test.py
index 194d90aa9c6..e3bee3b2a4d 100644
--- a/tests/system/suite_general/tst_create_proj_wizard/test.py
+++ b/tests/system/suite_general/tst_create_proj_wizard/test.py
@@ -61,7 +61,7 @@ def main():
         for template in dumpItems(templatesView.model(), templatesView.rootIndex()):
             template = template.replace(".", "\\.")
             # skip non-configurable
-            if not template in ["Qt Quick UI Prototype", "Auto Test Project",  # FIXME
+            if template not in ["Qt Quick UI Prototype", "Auto Test Project",  # FIXME
                                 "Qt for Python - Empty", "Qt for Python - Window"]:
                 availableProjectTypes.append({category:template})
     safeClickButton("Cancel")
diff --git a/tests/system/suite_general/tst_rename_file/test.py b/tests/system/suite_general/tst_rename_file/test.py
index ed13ee9a8e1..3f0907759af 100644
--- a/tests/system/suite_general/tst_rename_file/test.py
+++ b/tests/system/suite_general/tst_rename_file/test.py
@@ -114,11 +114,11 @@ def renameFile(projectDir, proFile, branch, oldname, newname):
                  "Comparing content of file before and after renaming")
     test.verify(waitFor("newname in safeReadFile(proFile)", 2000),
                 "Verify that new filename '%s' was added to pro-file." % newname)
-    if not oldname in newname:
-        test.verify(not oldname in readFile(proFile),
+    if oldname not in newname:
+        test.verify(oldname not in readFile(proFile),
                     "Verify that old filename '%s' was removed from pro-file." % oldname)
     if not (oldname.lower() == newname.lower() and platform.system() in ('Windows', 'Microsoft')):
-        test.verify(not oldname in os.listdir(projectDir),
+        test.verify(oldname not in os.listdir(projectDir),
                     "Verify that file with old name does not exist: %s" % oldFilePath)
 
 def safeReadFile(filename):