diff --git a/src/Ramstack.FileProviders/PrefixedFileProvider.cs b/src/Ramstack.FileProviders/PrefixedFileProvider.cs
index 9609e46..f41edf8 100644
--- a/src/Ramstack.FileProviders/PrefixedFileProvider.cs
+++ b/src/Ramstack.FileProviders/PrefixedFileProvider.cs
@@ -135,24 +135,77 @@ public void Dispose() =>
         var prefixSegments = new PathTokenizer(prefix).GetEnumerator();
         var filterSegments = new PathTokenizer(filter).GetEnumerator();
 
-        var list = new List<string>();
-
         while (prefixSegments.MoveNext() && filterSegments.MoveNext())
         {
             var fs = filterSegments.Current;
 
-            // The globstar '**' matches any number of remaining segments, including none
             if (fs is "**")
             {
-                // Add '**' and all remaining filter segments to the result.
-                do
-                {
-                    var segment = filterSegments.Current.ToString();
-                    list.Add(segment);
-                }
-                while (filterSegments.MoveNext());
-
-                return string.Join("/", list);
+                // The globstar '**' matches zero or more path segments.
+                // Once we encounter '**', we lose the ability to deterministically align
+                // the remaining filter segments with the remaining prefix segments.
+                //
+                // Why this matters:
+                //   We are transforming a filter defined over the 'outer' virtual path
+                //   into a filter for the 'inner' provider (mounted at 'prefix').
+                //   To do that precisely, we would need to know how many segments '**' consumes.
+                //
+                // However, this is fundamentally ambiguous:
+                //   - '**' may consume 0 segments
+                //   - '**' may consume N segments (including prefix tail segments)
+                //   - or it may match entirely within the underlying provider
+                //
+                // Example (false negative if we over-reduce):
+                //   prefix: /modules/profile/assets
+                //   filter: /modules/**/assets/*.js
+                //
+                //   Underlying provider may contain:
+                //     /src/_build/assets/main.js
+                //
+                //   Which corresponds to:
+                //     /modules/profile/assets/src/_build/assets/main.js
+                //
+                //   In this case:
+                //     '**/assets/*.js' --> MUST match
+                //     '*.js'           --> would NOT match
+                //
+                // Counter-example (false negative if we try to keep prefix tail):
+                //   prefix: /modules/profile/assets
+                //   filter: /modules/**/assets/*.js
+                //
+                //   Suppose 'assets' in the filter refers to the *prefix itself*,
+                //   and the underlying provider contains only flat files:
+                //     /main.js
+                //
+                //   (i.e. no nested 'assets/' directory inside the provider)
+                //
+                //   Then:
+                //     '*.js'             --> MUST match
+                //     '**/assets/*.js'   --> would NOT match
+                //
+                // Conclusion:
+                //   After '**', we cannot know whether subsequent segments belong
+                //   to the prefix or to the underlying provider.
+                //
+                // Therefore, any attempt to:
+                //   - consume prefix segments (--> '*.js')
+                //   - or preserve intermediate literals (--> '**/assets/*.js')
+                //   will break valid scenarios.
+                //
+                // Strategy:
+                //   - Preserve '**' to allow arbitrary depth
+                //   - Drop ambiguous intermediate segments
+                //   - Keep only the final segment if it is a file pattern (e.g. '*.js')
+                //
+                // This guarantees:
+                //   - No false negatives caused by prefix misalignment
+                //   - Possible false positives, which are acceptable for Watch()
+                while (filterSegments.MoveNext())
+                    fs = filterSegments.Current;
+
+                return fs is not "**"
+                    ? "**/" + fs.ToString()
+                    : "**";
             }
 
             if (fs is "*")
@@ -174,6 +227,8 @@ public void Dispose() =>
 
         if (!prefixSegments.MoveNext())
         {
+            var list = new List<string>();
+
             // All prefix segments have been matched and consumed successfully.
             // Append all remaining filter segments.
             while (filterSegments.MoveNext())
diff --git a/tests/Ramstack.FileProviders.Tests/PrefixedFileProviderTests.cs b/tests/Ramstack.FileProviders.Tests/PrefixedFileProviderTests.cs
index a88668b..da0591b 100644
--- a/tests/Ramstack.FileProviders.Tests/PrefixedFileProviderTests.cs
+++ b/tests/Ramstack.FileProviders.Tests/PrefixedFileProviderTests.cs
@@ -29,6 +29,12 @@ protected override DirectoryInfo GetDirectoryInfo() =>
 
     [TestCase("/modules/profile/assets", "/modules/**", ExpectedResult = "**")]
     [TestCase("/modules/profile/assets", "/modules/**/*.js", ExpectedResult = "**/*.js")]
+    [TestCase("/modules/profile/assets", "/modules/**/assets/*.js", ExpectedResult = "**/*.js")]
+    [TestCase("/modules/profile/assets", "/modules/**/profile/assets/*.{js,css}", ExpectedResult = "**/*.{js,css}")]
+    [TestCase("/modules/profile/assets", "/modules/**/profile/assets/**", ExpectedResult = "**")]
+    [TestCase("/modules/profile/assets", "/modules/**/profile/assets/**/*", ExpectedResult = "**/*")]
+    [TestCase("/modules/profile/assets", "/**/*.js", ExpectedResult = "**/*.js")]
+    [TestCase("/modules/profile/assets", "/**", ExpectedResult = "**")]
     [TestCase("/modules/profile/assets", "/modules/profile/*/*.js", ExpectedResult = "*.js")]
     [TestCase("/modules/profile/assets", "/modules/profile/{js,css,assets}/*.js", ExpectedResult = "*.js")]
     [TestCase("/modules/profile/assets", "/modules/{settings,profile}/{js,css,assets}/*.js", ExpectedResult = "*.js")]