diff --git a/osu.Game.Rulesets.Osu/Mods/OsuModAutopilot.cs b/osu.Game.Rulesets.Osu/Mods/OsuModAutopilot.cs
index fe46876050..d75f4c70d7 100644
--- a/osu.Game.Rulesets.Osu/Mods/OsuModAutopilot.cs
+++ b/osu.Game.Rulesets.Osu/Mods/OsuModAutopilot.cs
@@ -24,7 +24,8 @@ namespace osu.Game.Rulesets.Osu.Mods
         public override double ScoreMultiplier => 1;
         public override Type[] IncompatibleMods => new[] { typeof(OsuModSpunOut), typeof(ModRelax), typeof(ModSuddenDeath), typeof(ModNoFail), typeof(ModAutoplay) };
 
-        public bool AllowFail => false;
+        public bool PerformFail() => false;
+
         public bool RestartOnFail => false;
 
         private OsuInputManager inputManager;
diff --git a/osu.Game.Tests/NonVisual/CustomDataDirectoryTest.cs b/osu.Game.Tests/NonVisual/CustomDataDirectoryTest.cs
index e8f052cdeb..743c924bbd 100644
--- a/osu.Game.Tests/NonVisual/CustomDataDirectoryTest.cs
+++ b/osu.Game.Tests/NonVisual/CustomDataDirectoryTest.cs
@@ -223,7 +223,7 @@ namespace osu.Game.Tests.NonVisual
         [Test]
         public void TestMigrationToNestedTargetFails()
         {
-            using (HeadlessGameHost host = new CleanRunHeadlessGameHost(nameof(TestMigrationToSameTargetFails)))
+            using (HeadlessGameHost host = new CleanRunHeadlessGameHost(nameof(TestMigrationToNestedTargetFails)))
             {
                 try
                 {
@@ -233,6 +233,9 @@ namespace osu.Game.Tests.NonVisual
 
                     string subFolder = Path.Combine(customPath, "sub");
 
+                    if (Directory.Exists(subFolder))
+                        Directory.Delete(subFolder, true);
+
                     Directory.CreateDirectory(subFolder);
 
                     Assert.Throws<ArgumentException>(() => osu.Migrate(subFolder));
@@ -244,6 +247,33 @@ namespace osu.Game.Tests.NonVisual
             }
         }
 
+        [Test]
+        public void TestMigrationToSeeminglyNestedTarget()
+        {
+            using (HeadlessGameHost host = new CleanRunHeadlessGameHost(nameof(TestMigrationToSeeminglyNestedTarget)))
+            {
+                try
+                {
+                    var osu = loadOsu(host);
+
+                    Assert.DoesNotThrow(() => osu.Migrate(customPath));
+
+                    string seeminglySubFolder = customPath + "sub";
+
+                    if (Directory.Exists(seeminglySubFolder))
+                        Directory.Delete(seeminglySubFolder, true);
+
+                    Directory.CreateDirectory(seeminglySubFolder);
+
+                    osu.Migrate(seeminglySubFolder);
+                }
+                finally
+                {
+                    host.Exit();
+                }
+            }
+        }
+
         private OsuGameBase loadOsu(GameHost host)
         {
             var osu = new OsuGameBase();
diff --git a/osu.Game.Tests/Visual/Gameplay/TestSceneReplay.cs b/osu.Game.Tests/Visual/Gameplay/TestSceneReplay.cs
index e82722e7a2..1908988739 100644
--- a/osu.Game.Tests/Visual/Gameplay/TestSceneReplay.cs
+++ b/osu.Game.Tests/Visual/Gameplay/TestSceneReplay.cs
@@ -33,7 +33,8 @@ namespace osu.Game.Tests.Visual.Gameplay
         {
             public new ScoreProcessor ScoreProcessor => base.ScoreProcessor;
             public new HUDOverlay HUDOverlay => base.HUDOverlay;
-            public new bool AllowFail => base.AllowFail;
+
+            public bool AllowFail => base.CheckModsAllowFailure();
 
             protected override bool PauseOnFocusLost => false;
 
diff --git a/osu.Game/IO/OsuStorage.cs b/osu.Game/IO/OsuStorage.cs
index e3888c0c28..5393cbf7ae 100644
--- a/osu.Game/IO/OsuStorage.cs
+++ b/osu.Game/IO/OsuStorage.cs
@@ -48,10 +48,14 @@ namespace osu.Game.IO
             var source = new DirectoryInfo(GetFullPath("."));
             var destination = new DirectoryInfo(newLocation);
 
-            if (source.FullName == destination.FullName)
+            // using Uri is the easiest way to check equality and contains (https://stackoverflow.com/a/7710620)
+            var sourceUri = new Uri(source.FullName + Path.DirectorySeparatorChar);
+            var destinationUri = new Uri(destination.FullName + Path.DirectorySeparatorChar);
+
+            if (sourceUri == destinationUri)
                 throw new ArgumentException("Destination provided is already the current location", nameof(newLocation));
 
-            if (destination.FullName.Contains(source.FullName))
+            if (sourceUri.IsBaseOf(destinationUri))
                 throw new ArgumentException("Destination provided is inside the source", nameof(newLocation));
 
             // ensure the new location has no files present, else hard abort
diff --git a/osu.Game/Rulesets/Mods/IApplicableFailOverride.cs b/osu.Game/Rulesets/Mods/IApplicableFailOverride.cs
index 120bfc9a23..8c99d739cb 100644
--- a/osu.Game/Rulesets/Mods/IApplicableFailOverride.cs
+++ b/osu.Game/Rulesets/Mods/IApplicableFailOverride.cs
@@ -11,10 +11,11 @@ namespace osu.Game.Rulesets.Mods
         /// <summary>
         /// Whether we should allow failing at the current point in time.
         /// </summary>
-        bool AllowFail { get; }
+        /// <returns>Whether the fail should be allowed to proceed. Return false to block.</returns>
+        bool PerformFail();
 
         /// <summary>
-        /// Whether we want to restart on fail. Only used if <see cref="AllowFail"/> is true.
+        /// Whether we want to restart on fail. Only used if <see cref="PerformFail"/> returns true.
         /// </summary>
         bool RestartOnFail { get; }
     }
diff --git a/osu.Game/Rulesets/Mods/ModAutoplay.cs b/osu.Game/Rulesets/Mods/ModAutoplay.cs
index e51b8b6457..945dd444be 100644
--- a/osu.Game/Rulesets/Mods/ModAutoplay.cs
+++ b/osu.Game/Rulesets/Mods/ModAutoplay.cs
@@ -27,7 +27,8 @@ namespace osu.Game.Rulesets.Mods
         public override string Description => "Watch a perfect automated play through the song.";
         public override double ScoreMultiplier => 1;
 
-        public bool AllowFail => false;
+        public bool PerformFail() => false;
+
         public bool RestartOnFail => false;
 
         public override Type[] IncompatibleMods => new[] { typeof(ModRelax), typeof(ModSuddenDeath), typeof(ModNoFail) };
diff --git a/osu.Game/Rulesets/Mods/ModBlockFail.cs b/osu.Game/Rulesets/Mods/ModBlockFail.cs
index 7d7ecfa416..1fde5abad4 100644
--- a/osu.Game/Rulesets/Mods/ModBlockFail.cs
+++ b/osu.Game/Rulesets/Mods/ModBlockFail.cs
@@ -14,7 +14,7 @@ namespace osu.Game.Rulesets.Mods
         /// <summary>
         /// We never fail, 'yo.
         /// </summary>
-        public bool AllowFail => false;
+        public bool PerformFail() => false;
 
         public bool RestartOnFail => false;
 
diff --git a/osu.Game/Rulesets/Mods/ModEasy.cs b/osu.Game/Rulesets/Mods/ModEasy.cs
index c1c4124b98..7cf9656810 100644
--- a/osu.Game/Rulesets/Mods/ModEasy.cs
+++ b/osu.Game/Rulesets/Mods/ModEasy.cs
@@ -48,17 +48,14 @@ namespace osu.Game.Rulesets.Mods
             retries = Retries.Value;
         }
 
-        public bool AllowFail
+        public bool PerformFail()
         {
-            get
-            {
-                if (retries == 0) return true;
+            if (retries == 0) return true;
 
-                health.Value = health.MaxValue;
-                retries--;
+            health.Value = health.MaxValue;
+            retries--;
 
-                return false;
-            }
+            return false;
         }
 
         public bool RestartOnFail => false;
diff --git a/osu.Game/Rulesets/Mods/ModSuddenDeath.cs b/osu.Game/Rulesets/Mods/ModSuddenDeath.cs
index 8799431f1d..df10262845 100644
--- a/osu.Game/Rulesets/Mods/ModSuddenDeath.cs
+++ b/osu.Game/Rulesets/Mods/ModSuddenDeath.cs
@@ -20,7 +20,8 @@ namespace osu.Game.Rulesets.Mods
         public override bool Ranked => true;
         public override Type[] IncompatibleMods => new[] { typeof(ModNoFail), typeof(ModRelax), typeof(ModAutoplay) };
 
-        public bool AllowFail => true;
+        public bool PerformFail() => true;
+
         public bool RestartOnFail => true;
 
         public void ApplyToHealthProcessor(HealthProcessor healthProcessor)
diff --git a/osu.Game/Screens/Play/Player.cs b/osu.Game/Screens/Play/Player.cs
index a2735c8c55..1ec3a69b24 100644
--- a/osu.Game/Screens/Play/Player.cs
+++ b/osu.Game/Screens/Play/Player.cs
@@ -105,7 +105,7 @@ namespace osu.Game.Screens.Play
         /// Whether failing should be allowed.
         /// By default, this checks whether all selected mods allow failing.
         /// </summary>
-        protected virtual bool AllowFail => Mods.Value.OfType<IApplicableFailOverride>().All(m => m.AllowFail);
+        protected virtual bool CheckModsAllowFailure() => Mods.Value.OfType<IApplicableFailOverride>().All(m => m.PerformFail());
 
         private readonly bool allowPause;
         private readonly bool showResults;
@@ -485,7 +485,7 @@ namespace osu.Game.Screens.Play
 
         private bool onFail()
         {
-            if (!AllowFail)
+            if (!CheckModsAllowFailure())
                 return false;
 
             HasFailed = true;
diff --git a/osu.Game/Screens/Play/ReplayPlayer.cs b/osu.Game/Screens/Play/ReplayPlayer.cs
index 0d2ddb7b01..f0c76163f1 100644
--- a/osu.Game/Screens/Play/ReplayPlayer.cs
+++ b/osu.Game/Screens/Play/ReplayPlayer.cs
@@ -12,7 +12,7 @@ namespace osu.Game.Screens.Play
         private readonly Score score;
 
         // Disallow replays from failing. (see https://github.com/ppy/osu/issues/6108)
-        protected override bool AllowFail => false;
+        protected override bool CheckModsAllowFailure() => false;
 
         public ReplayPlayer(Score score, bool allowPause = true, bool showResults = true)
             : base(allowPause, showResults)
diff --git a/osu.Game/Tests/Visual/ModPerfectTestScene.cs b/osu.Game/Tests/Visual/ModPerfectTestScene.cs
index 5948283428..95a62bbf65 100644
--- a/osu.Game/Tests/Visual/ModPerfectTestScene.cs
+++ b/osu.Game/Tests/Visual/ModPerfectTestScene.cs
@@ -41,7 +41,7 @@ namespace osu.Game.Tests.Visual
             {
             }
 
-            protected override bool AllowFail => true;
+            protected override bool CheckModsAllowFailure() => true;
 
             public bool CheckFailed(bool failed)
             {
diff --git a/osu.Game/Tests/Visual/ModTestScene.cs b/osu.Game/Tests/Visual/ModTestScene.cs
index 8b41fb5075..b5b3084097 100644
--- a/osu.Game/Tests/Visual/ModTestScene.cs
+++ b/osu.Game/Tests/Visual/ModTestScene.cs
@@ -64,12 +64,14 @@ namespace osu.Game.Tests.Visual
 
         protected class ModTestPlayer : TestPlayer
         {
-            protected override bool AllowFail { get; }
+            private readonly bool allowFail;
+
+            protected override bool CheckModsAllowFailure() => allowFail;
 
             public ModTestPlayer(bool allowFail)
                 : base(false, false)
             {
-                AllowFail = allowFail;
+                this.allowFail = allowFail;
             }
         }