diff --git a/src/common/JoyMap.cxx b/src/common/JoyMap.cxx
index 623245e77..e1577b50b 100644
--- a/src/common/JoyMap.cxx
+++ b/src/common/JoyMap.cxx
@@ -98,9 +98,7 @@ Event::Type JoyMap::get(const EventMode mode, const int button,
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 bool JoyMap::check(const JoyMapping& mapping) const
 {
-  const auto find = myMap.find(mapping);
-
-  return (find != myMap.end());
+  return myMap.contains(mapping);
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
diff --git a/src/common/KeyMap.cxx b/src/common/KeyMap.cxx
index d0a9c31d2..fab0d064f 100644
--- a/src/common/KeyMap.cxx
+++ b/src/common/KeyMap.cxx
@@ -122,9 +122,7 @@ Event::Type KeyMap::get(const EventMode mode, const int key, const int mod) cons
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 bool KeyMap::check(const Mapping& mapping) const
 {
-  const auto find = myMap.find(convertMod(mapping));
-
-  return (find != myMap.end());
+  return myMap.contains(convertMod(mapping));
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
diff --git a/src/common/PJoystickHandler.cxx b/src/common/PJoystickHandler.cxx
index fe269c690..59216fbc4 100644
--- a/src/common/PJoystickHandler.cxx
+++ b/src/common/PJoystickHandler.cxx
@@ -714,33 +714,33 @@ EventMode PhysicalJoystickHandler::getEventMode(const Event::Type event,
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 bool PhysicalJoystickHandler::isJoystickEvent(const Event::Type event)
 {
-  return LeftJoystickEvents.find(event) != LeftJoystickEvents.end()
-    || QTJoystick3Events.find(event) != QTJoystick3Events.end()
-    || RightJoystickEvents.find(event) != RightJoystickEvents.end()
-    || QTJoystick4Events.find(event) != QTJoystick4Events.end();
+  return LeftJoystickEvents.contains(event)
+    || QTJoystick3Events.contains(event)
+    || RightJoystickEvents.contains(event)
+    || QTJoystick4Events.contains(event);
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 bool PhysicalJoystickHandler::isPaddleEvent(const Event::Type event)
 {
-  return LeftPaddlesEvents.find(event) != LeftPaddlesEvents.end()
-    || QTPaddles3Events.find(event) != QTPaddles3Events.end()
-    || RightPaddlesEvents.find(event) != RightPaddlesEvents.end()
-    || QTPaddles4Events.find(event) != QTPaddles4Events.end();
+  return LeftPaddlesEvents.contains(event)
+    || QTPaddles3Events.contains(event)
+    || RightPaddlesEvents.contains(event)
+    || QTPaddles4Events.contains(event);
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 bool PhysicalJoystickHandler::isKeyboardEvent(const Event::Type event)
 {
-  return LeftKeyboardEvents.find(event) != LeftKeyboardEvents.end()
-    || RightKeyboardEvents.find(event) != RightKeyboardEvents.end();
+  return LeftKeyboardEvents.contains(event)
+    || RightKeyboardEvents.contains(event);
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 bool PhysicalJoystickHandler::isDrivingEvent(const Event::Type event)
 {
-  return LeftDrivingEvents.find(event) != LeftDrivingEvents.end()
-    || RightDrivingEvents.find(event) != RightDrivingEvents.end();
+  return LeftDrivingEvents.contains(event)
+    || RightDrivingEvents.contains(event);
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
diff --git a/src/common/PKeyboardHandler.cxx b/src/common/PKeyboardHandler.cxx
index f4ce5f556..b4ce96ab9 100644
--- a/src/common/PKeyboardHandler.cxx
+++ b/src/common/PKeyboardHandler.cxx
@@ -446,33 +446,33 @@ EventMode PhysicalKeyboardHandler::getEventMode(const Event::Type event,
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 bool PhysicalKeyboardHandler::isJoystickEvent(const Event::Type event)
 {
-  return LeftJoystickEvents.find(event) != LeftJoystickEvents.end()
-    || QTJoystick3Events.find(event) != QTJoystick3Events.end()
-    || RightJoystickEvents.find(event) != RightJoystickEvents.end()
-    || QTJoystick4Events.find(event) != QTJoystick4Events.end();
+  return LeftJoystickEvents.contains(event)
+    || QTJoystick3Events.contains(event)
+    || RightJoystickEvents.contains(event)
+    || QTJoystick4Events.contains(event);
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 bool PhysicalKeyboardHandler::isPaddleEvent(const Event::Type event)
 {
-  return LeftPaddlesEvents.find(event) != LeftPaddlesEvents.end()
-    || QTPaddles3Events.find(event) != QTPaddles3Events.end()
-    || RightPaddlesEvents.find(event) != RightPaddlesEvents.end()
-    || QTPaddles4Events.find(event) != QTPaddles4Events.end();
+  return LeftPaddlesEvents.contains(event)
+    || QTPaddles3Events.contains(event)
+    || RightPaddlesEvents.contains(event)
+    || QTPaddles4Events.contains(event);
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 bool PhysicalKeyboardHandler::isKeyboardEvent(const Event::Type event)
 {
-  return LeftKeyboardEvents.find(event) != LeftKeyboardEvents.end()
-    || RightKeyboardEvents.find(event) != RightKeyboardEvents.end();
+  return LeftKeyboardEvents.contains(event)
+    || RightKeyboardEvents.contains(event);
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 bool PhysicalKeyboardHandler::isDrivingEvent(const Event::Type event)
 {
-  return LeftDrivingEvents.find(event) != LeftDrivingEvents.end()
-    || RightDrivingEvents.find(event) != RightDrivingEvents.end();
+  return LeftDrivingEvents.contains(event)
+    || RightDrivingEvents.contains(event);
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
diff --git a/src/common/main.cxx b/src/common/main.cxx
index e342e2a9e..701ade014 100644
--- a/src/common/main.cxx
+++ b/src/common/main.cxx
@@ -140,12 +140,11 @@ void parseCommandLine(int ac, const char* const av[],
 void checkForCustomBaseDir(Settings::Options& options)
 {
   // If both of these are activated, the 'base in app dir' takes precedence
-  auto it = options.find("baseinappdir");
-  if(it != options.end())
+  if(options.contains("baseinappdir"))
     OSystem::overrideBaseDirWithApp();
   else
   {
-    it = options.find("basedir");
+    auto it = options.find("basedir");
     if(it != options.end())
       OSystem::overrideBaseDir(it->second.toString());
   }
diff --git a/src/common/repository/sqlite/StellaDb.cxx b/src/common/repository/sqlite/StellaDb.cxx
index 7ad4cb823..56a4d45fc 100644
--- a/src/common/repository/sqlite/StellaDb.cxx
+++ b/src/common/repository/sqlite/StellaDb.cxx
@@ -191,8 +191,7 @@ void StellaDb::importOldPropset(const FSNode& node)
 
     if (props.empty())
       break;
-    if ((props.find("Cart.MD5") == props.end()) ||
-         props["Cart.MD5"].toString().empty())
+    if (!props.contains("Cart.MD5") || props["Cart.MD5"].toString().empty())
       continue;
 
     myPropertyRepository->get(props["Cart.MD5"].toString())->save(props);
diff --git a/src/debugger/CartDebug.cxx b/src/debugger/CartDebug.cxx
index 9932f48a1..31ea780cd 100644
--- a/src/debugger/CartDebug.cxx
+++ b/src/debugger/CartDebug.cxx
@@ -1331,7 +1331,7 @@ string CartDebug::saveDisassembly(string path)
       const bool stackUsed = (mySystem.getAccessFlags(addr|0x100) & (Device::DATA | Device::WRITE));
 
       if (myReserved.ZPRAM[addr - 0x80] &&
-          myUserLabels.find(addr) == myUserLabels.end()) {
+          !myUserLabels.contains(addr)) {
         if (addLine)
           out << "\n";
         out << ALIGN(16) << ourZPMnemonic[addr - 0x80] << "= $"
diff --git a/src/debugger/Debugger.cxx b/src/debugger/Debugger.cxx
index d8cf34318..18878a72d 100644
--- a/src/debugger/Debugger.cxx
+++ b/src/debugger/Debugger.cxx
@@ -800,8 +800,7 @@ bool Debugger::isBuiltinFunction(string_view name)
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 bool Debugger::delFunction(string_view name)
 {
-  const auto& iter = myFunctions.find(name);
-  if(iter == myFunctions.end())
+  if(!myFunctions.contains(name))
     return false;
 
   // We never want to delete built-in functions
@@ -810,8 +809,7 @@ bool Debugger::delFunction(string_view name)
 
   myFunctions.erase(string{name});
 
-  const auto& def_iter = myFunctionDefs.find(name);
-  if(def_iter == myFunctionDefs.end())
+  if(!myFunctionDefs.contains(name))
     return false;
 
   myFunctionDefs.erase(string{name});
diff --git a/src/gui/FavoritesManager.cxx b/src/gui/FavoritesManager.cxx
index f00ae41d5..66fffbcb1 100644
--- a/src/gui/FavoritesManager.cxx
+++ b/src/gui/FavoritesManager.cxx
@@ -169,7 +169,7 @@ bool FavoritesManager::toggleUser(string_view path)
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 bool FavoritesManager::existsUser(string_view path) const
 {
-  return myUserSet.find(string{path}) != myUserSet.end();  // TODO: fixed in C++20
+  return myUserSet.contains(string{path});
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
diff --git a/src/gui/LauncherDialog.cxx b/src/gui/LauncherDialog.cxx
index e7e12f9fd..ce49533b2 100644
--- a/src/gui/LauncherDialog.cxx
+++ b/src/gui/LauncherDialog.cxx
@@ -427,8 +427,7 @@ const string& LauncherDialog::selectedRomMD5()
     myMD5List.clear();
 
   // Lookup MD5, and if not present, cache it
-  const auto iter = myMD5List.find(currentNode().getPath());
-  if(iter == myMD5List.end())
+  if(!myMD5List.contains(currentNode().getPath()))
     myMD5List[currentNode().getPath()] = OSystem::getROMMD5(currentNode());
 
   return myMD5List[currentNode().getPath()];