diff --git a/src/libraries/System.IO.FileSystem.Watcher/src/System.IO.FileSystem.Watcher.csproj b/src/libraries/System.IO.FileSystem.Watcher/src/System.IO.FileSystem.Watcher.csproj
index 37a53d008a572d..469005b661d886 100644
--- a/src/libraries/System.IO.FileSystem.Watcher/src/System.IO.FileSystem.Watcher.csproj
+++ b/src/libraries/System.IO.FileSystem.Watcher/src/System.IO.FileSystem.Watcher.csproj
@@ -28,7 +28,7 @@
     <Compile Include="$(CommonPath)System\IO\PathInternal.CaseSensitivity.cs"
              Link="Common\System\IO\PathInternal.CaseSensitivity.cs" />
     <Compile Include="$(CommonPath)System\IO\PathInternal.cs"
-            Link="Common\System\IO\PathInternal.cs" />
+             Link="Common\System\IO\PathInternal.cs" />
     <Compile Include="$(CommonPath)System\Text\ValueStringBuilder.cs"
              Link="Common\System\Text\ValueStringBuilder.cs" />
   </ItemGroup>
diff --git a/src/libraries/System.IO.FileSystem.Watcher/src/System/IO/FileSystemEventArgs.cs b/src/libraries/System.IO.FileSystem.Watcher/src/System/IO/FileSystemEventArgs.cs
index 5795394e13dfe7..a83e551abc396e 100644
--- a/src/libraries/System.IO.FileSystem.Watcher/src/System/IO/FileSystemEventArgs.cs
+++ b/src/libraries/System.IO.FileSystem.Watcher/src/System/IO/FileSystemEventArgs.cs
@@ -21,14 +21,24 @@ public FileSystemEventArgs(WatcherChangeTypes changeType, string directory, stri
 
             _changeType = changeType;
             _name = name;
+            _fullPath = Combine(directory, name);
+        }
 
-            if (directory.Length == 0) // empty directory means current working dir
-            {
-                directory = ".";
-            }
+        /// <summary>Combines a directory path and a relative file name into a single path.</summary>
+        /// <param name="directory">The directory path.</param>
+        /// <param name="name">The file name.</param>
+        /// <returns>The combined name.</returns>
+        /// <remarks>
+        /// This is like Path.Combine, except without argument validation,
+        /// and a separator is used even if the name argument is empty.
+        /// </remarks>
+        internal static string Combine(string directory, string? name)
+        {
+            bool hasSeparator = directory.Length != 0 && PathInternal.IsDirectorySeparator(directory[^1]);
 
-            string fullDirectoryPath = Path.GetFullPath(directory);
-            _fullPath = string.IsNullOrEmpty(name) ? PathInternal.EnsureTrailingSeparator(fullDirectoryPath) : Path.Join(fullDirectoryPath, name);
+            return hasSeparator ?
+                directory + name :
+                directory + Path.DirectorySeparatorChar + name;
         }
 
         /// <devdoc>
diff --git a/src/libraries/System.IO.FileSystem.Watcher/src/System/IO/RenamedEventArgs.cs b/src/libraries/System.IO.FileSystem.Watcher/src/System/IO/RenamedEventArgs.cs
index 17221c568dc32a..9d254e0c1f5760 100644
--- a/src/libraries/System.IO.FileSystem.Watcher/src/System/IO/RenamedEventArgs.cs
+++ b/src/libraries/System.IO.FileSystem.Watcher/src/System/IO/RenamedEventArgs.cs
@@ -18,14 +18,7 @@ public RenamedEventArgs(WatcherChangeTypes changeType, string directory, string?
             : base(changeType, directory, name)
         {
             _oldName = oldName;
-
-            if (directory.Length == 0) // empty directory means current working dir
-            {
-                directory = ".";
-            }
-
-            string fullDirectoryPath = Path.GetFullPath(directory);
-            _oldFullPath = string.IsNullOrEmpty(oldName) ? PathInternal.EnsureTrailingSeparator(fullDirectoryPath) : Path.Join(fullDirectoryPath, oldName);
+            _oldFullPath = Combine(directory, oldName);
         }
 
         /// <devdoc>
diff --git a/src/libraries/System.IO.FileSystem.Watcher/tests/Args.FileSystemEventArgs.cs b/src/libraries/System.IO.FileSystem.Watcher/tests/Args.FileSystemEventArgs.cs
index d3abb21d9a2d3f..39e95c72c838ac 100644
--- a/src/libraries/System.IO.FileSystem.Watcher/tests/Args.FileSystemEventArgs.cs
+++ b/src/libraries/System.IO.FileSystem.Watcher/tests/Args.FileSystemEventArgs.cs
@@ -8,10 +8,10 @@ namespace System.IO.Tests
     public class FileSystemEventArgsTests
     {
         [Theory]
-        [InlineData(WatcherChangeTypes.Changed, "bar", "foo.txt")]
-        [InlineData(WatcherChangeTypes.All, "bar", "foo.txt")]
-        [InlineData((WatcherChangeTypes)0, "bar", "")]
-        [InlineData((WatcherChangeTypes)0, "bar", null)]
+        [InlineData(WatcherChangeTypes.Changed, "C:", "foo.txt")]
+        [InlineData(WatcherChangeTypes.All, "C:", "foo.txt")]
+        [InlineData((WatcherChangeTypes)0, "", "")]
+        [InlineData((WatcherChangeTypes)0, "", null)]
         public static void FileSystemEventArgs_ctor_NonPathPropertiesAreSetCorrectly(WatcherChangeTypes changeType, string directory, string name)
         {
             FileSystemEventArgs args = new FileSystemEventArgs(changeType, directory, name);
@@ -59,44 +59,52 @@ public static void FileSystemEventArgs_ctor_DirectoryIsAbsolutePath_Unix(string
 
         [Theory]
         [PlatformSpecific(TestPlatforms.Windows)]
-        [InlineData("", "")]
-        [InlineData("", "foo.txt")]
-        [InlineData("bar", "foo.txt")]
-        [InlineData("bar\\baz", "foo.txt")]
-        public static void FileSystemEventArgs_ctor_DirectoryIsRelativePath_Windows(string directory, string name)
+        [InlineData("", "", "\\")]
+        [InlineData("", "foo.txt", "\\foo.txt")]
+        [InlineData("bar", "foo.txt", "bar\\foo.txt")]
+        [InlineData("bar\\baz", "foo.txt", "bar\\baz\\foo.txt")]
+        public static void FileSystemEventArgs_ctor_DirectoryIsRelativePath_Windows(string directory, string name, string expectedFullPath)
         {
             FileSystemEventArgs args = new FileSystemEventArgs(WatcherChangeTypes.All, directory, name);
 
-            var expectedDirectory = PathInternal.EnsureTrailingSeparator(Path.Combine(Directory.GetCurrentDirectory(), directory));
-            Assert.Equal(Path.Combine(expectedDirectory, name), args.FullPath);
+            Assert.Equal(expectedFullPath, args.FullPath);
         }
 
         [Theory]
         [PlatformSpecific(TestPlatforms.AnyUnix)]
-        [InlineData("", "")]
-        [InlineData("", "foo.txt")]
-        [InlineData("   ", "    ")]
-        [InlineData("   ", "foo.txt")]
-        [InlineData("bar", "foo.txt")]
-        [InlineData("bar/baz", "foo.txt")]
-        public static void FileSystemEventArgs_ctor_DirectoryIsRelativePath_Unix(string directory, string name)
+        [InlineData("", "", "/")]
+        [InlineData("", "foo.txt", "/foo.txt")]
+        [InlineData("   ", "    ", "   /    ")]
+        [InlineData("   ", "foo.txt", "   /foo.txt")]
+        [InlineData("bar", "foo.txt", "bar/foo.txt")]
+        [InlineData("bar/baz", "foo.txt", "bar/baz/foo.txt")]
+        public static void FileSystemEventArgs_ctor_DirectoryIsRelativePath_Unix(string directory, string name, string expectedFullPath)
         {
             FileSystemEventArgs args = new FileSystemEventArgs(WatcherChangeTypes.All, directory, name);
 
-            var expectedDirectory = PathInternal.EnsureTrailingSeparator(Path.Combine(Directory.GetCurrentDirectory(), directory));
-            Assert.Equal(Path.Combine(expectedDirectory, name), args.FullPath);
+            Assert.Equal(expectedFullPath, args.FullPath);
         }
 
         [Theory]
-        [InlineData("bar", "")]
-        [InlineData("bar", null)]
-        public static void FileSystemEventArgs_ctor_When_EmptyFileName_Then_FullPathReturnsTheDirectoryFullPath_WithTrailingSeparator(string directory, string name)
+        [PlatformSpecific(TestPlatforms.Windows)]
+        [InlineData("bar", "", "bar\\")]
+        [InlineData("bar", null, "bar\\")]
+        public static void FileSystemEventArgs_ctor_EmptyFileName_Windows(string directory, string name, string expectedFullPath)
         {
             FileSystemEventArgs args = new FileSystemEventArgs(WatcherChangeTypes.All, directory, name);
 
-            directory = PathInternal.EnsureTrailingSeparator(directory);
+            Assert.Equal(expectedFullPath, args.FullPath);
+        }
 
-            Assert.Equal(PathInternal.EnsureTrailingSeparator(Directory.GetCurrentDirectory()) + directory, args.FullPath);
+        [Theory]
+        [PlatformSpecific(TestPlatforms.AnyUnix)]
+        [InlineData("bar", "", "bar/")]
+        [InlineData("bar", null, "bar/")]
+        public static void FileSystemEventArgs_ctor_EmptyFileName_Unix(string directory, string name, string expectedFullPath)
+        {
+            FileSystemEventArgs args = new FileSystemEventArgs(WatcherChangeTypes.All, directory, name);
+
+            Assert.Equal(expectedFullPath, args.FullPath);
         }
 
         [Fact]
diff --git a/src/libraries/System.IO.FileSystem.Watcher/tests/Args.RenamedEventArgs.cs b/src/libraries/System.IO.FileSystem.Watcher/tests/Args.RenamedEventArgs.cs
index 3a504a668b0872..d92324fc53291b 100644
--- a/src/libraries/System.IO.FileSystem.Watcher/tests/Args.RenamedEventArgs.cs
+++ b/src/libraries/System.IO.FileSystem.Watcher/tests/Args.RenamedEventArgs.cs
@@ -47,43 +47,52 @@ public static void RenamedEventArgs_ctor_OldFullPath_DirectoryIsAnAbsolutePath_U
 
         [Theory]
         [PlatformSpecific(TestPlatforms.Windows)]
-        [InlineData("", "", "")]
-        [InlineData("", "foo.txt", "bar.txt")]
-        [InlineData("bar", "foo.txt", "bar.txt")]
-        [InlineData("bar\\baz", "foo.txt", "bar.txt")]
-        public static void RenamedEventArgs_ctor_OldFullPath_DirectoryIsRelativePath_Windows(string directory, string name, string oldName)
+        [InlineData("", "", "", "\\")]
+        [InlineData("", "foo.txt", "bar.txt", "\\bar.txt")]
+        [InlineData("bar", "foo.txt", "bar.txt", "bar\\bar.txt")]
+        [InlineData("bar\\baz", "foo.txt", "bar.txt", "bar\\baz\\bar.txt")]
+        public static void RenamedEventArgs_ctor_OldFullPath_DirectoryIsRelativePath_Windows(string directory, string name, string oldName, string expectedOldFullPath)
         {
             RenamedEventArgs args = new RenamedEventArgs(WatcherChangeTypes.All, directory, name, oldName);
 
-            var expectedDirectory = PathInternal.EnsureTrailingSeparator(Path.Combine(Directory.GetCurrentDirectory(), directory));
-            Assert.Equal(Path.Combine(expectedDirectory, oldName), args.OldFullPath);
+            Assert.Equal(expectedOldFullPath, args.OldFullPath);
         }
 
         [Theory]
         [PlatformSpecific(TestPlatforms.AnyUnix)]
-        [InlineData("", "", "")]
-        [InlineData("", "foo.txt", "bar.txt")]
-        [InlineData("bar", "foo.txt", "bar.txt")]
-        [InlineData("bar/baz", "foo.txt", "bar.txt")]
-        public static void RenamedEventArgs_ctor_OldFullPath_DirectoryIsRelativePath_Unix(string directory, string name, string oldName)
+        [InlineData("", "", "", "/")]
+        [InlineData("", "foo.txt", "bar.txt", "/bar.txt")]
+        [InlineData("bar", "foo.txt", "bar.txt", "bar/bar.txt")]
+        [InlineData("bar/baz", "foo.txt", "bar.txt", "bar/baz/bar.txt")]
+        public static void RenamedEventArgs_ctor_OldFullPath_DirectoryIsRelativePath_Unix(string directory, string name, string oldName, string expectedOldFullPath)
         {
             RenamedEventArgs args = new RenamedEventArgs(WatcherChangeTypes.All, directory, name, oldName);
 
-            var expectedDirectory = PathInternal.EnsureTrailingSeparator(Path.Combine(Directory.GetCurrentDirectory(), directory));
-            Assert.Equal(Path.Combine(expectedDirectory, oldName), args.OldFullPath);
+            Assert.Equal(expectedOldFullPath, args.OldFullPath);
         }
 
         [Theory]
-        [InlineData("bar", "", "")]
-        [InlineData("bar", null, null)]
-        [InlineData("bar", "foo.txt", null)]
-        public static void RenamedEventArgs_ctor_When_EmptyOldFileName_Then_OldFullPathReturnsTheDirectoryFullPath_WithTrailingSeparator(string directory, string name, string oldName)
+        [PlatformSpecific(TestPlatforms.Windows)]
+        [InlineData("bar", "", "", "bar\\")]
+        [InlineData("bar", null, null, "bar\\")]
+        [InlineData("bar", "foo.txt", null, "bar\\")]
+        public static void RenamedEventArgs_ctor_EmptyOldFileName_Windows(string directory, string name, string oldName, string expectedOldFullPath)
         {
             RenamedEventArgs args = new RenamedEventArgs(WatcherChangeTypes.All, directory, name, oldName);
 
-            directory = PathInternal.EnsureTrailingSeparator(directory);
+            Assert.Equal(expectedOldFullPath, args.OldFullPath);
+        }
 
-            Assert.Equal(PathInternal.EnsureTrailingSeparator(Directory.GetCurrentDirectory()) + directory, args.OldFullPath);
+        [Theory]
+        [PlatformSpecific(TestPlatforms.AnyUnix)]
+        [InlineData("bar", "", "", "bar/")]
+        [InlineData("bar", null, null, "bar/")]
+        [InlineData("bar", "foo.txt", null, "bar/")]
+        public static void RenamedEventArgs_ctor_EmptyOldFileName_Unix(string directory, string name, string oldName, string expectedOldFullPath)
+        {
+            RenamedEventArgs args = new RenamedEventArgs(WatcherChangeTypes.All, directory, name, oldName);
+
+            Assert.Equal(expectedOldFullPath, args.OldFullPath);
         }
 
         [Fact]