diff --git a/src/Compilers/Core/CodeAnalysisTest/FileSystem/PathUtilitiesTests.cs b/src/Compilers/Core/CodeAnalysisTest/FileSystem/PathUtilitiesTests.cs
index 16ecf206029d7..c660ffa62b568 100644
--- a/src/Compilers/Core/CodeAnalysisTest/FileSystem/PathUtilitiesTests.cs
+++ b/src/Compilers/Core/CodeAnalysisTest/FileSystem/PathUtilitiesTests.cs
@@ -383,5 +383,21 @@ public void CombinePaths_DifferentFromPathCombine(string expected, string path1,
         {
             Assert.Equal(expected, PathUtilities.CombinePaths(path1, path2));
         }
+
+        [ConditionalFact(typeof(WindowsOnly)), WorkItem(51602, @"https://github.com/dotnet/roslyn/issues/51602")]
+        public void GetRelativePath_EnsureNo_IndexOutOfRangeException_Windows()
+        {
+            var expected = "";
+            var result = PathUtilities.GetRelativePath(@"C:\A\B\", @"C:\A\B");
+            Assert.Equal(expected, result);
+        }
+
+        [ConditionalFact(typeof(UnixLikeOnly)), WorkItem(51602, @"https://github.com/dotnet/roslyn/issues/51602")]
+        public void GetRelativePath_EnsureNo_IndexOutOfRangeException_Unix()
+        {
+            var expected = "";
+            var result = PathUtilities.GetRelativePath(@"/A/B/", @"/A/B");
+            Assert.Equal(expected, result);
+        }
     }
 }
diff --git a/src/Compilers/Core/Portable/FileSystem/PathUtilities.cs b/src/Compilers/Core/Portable/FileSystem/PathUtilities.cs
index 297dec288f528..b3b7cedccfe78 100644
--- a/src/Compilers/Core/Portable/FileSystem/PathUtilities.cs
+++ b/src/Compilers/Core/Portable/FileSystem/PathUtilities.cs
@@ -534,6 +534,9 @@ public static string GetRelativePath(string directory, string fullPath)
         {
             string relativePath = string.Empty;
 
+            directory = TrimTrailingSeparators(directory);
+            fullPath = TrimTrailingSeparators(fullPath);
+
             if (IsChildPath(directory, fullPath))
             {
                 return GetRelativeChildPath(directory, fullPath);