diff --git a/platform/util-rt/src/com/intellij/openapi/util/io/FileUtilRt.java b/platform/util-rt/src/com/intellij/openapi/util/io/FileUtilRt.java
index 396d39ce2f2b..57d13e51e736 100644
--- a/platform/util-rt/src/com/intellij/openapi/util/io/FileUtilRt.java
+++ b/platform/util-rt/src/com/intellij/openapi/util/io/FileUtilRt.java
@@ -210,18 +210,14 @@ public class FileUtilRt {
   }
 
   @Nullable
-  public static String getRelativePath(@NotNull String basePath,
-                                       @NotNull String filePath,
-                                       final char separator,
-                                       final boolean caseSensitive) {
+  public static String getRelativePath(@NotNull String basePath, @NotNull String filePath, final char separator, final boolean caseSensitive) {
     basePath = ensureEnds(basePath, separator);
 
-    String basePathToCompare = caseSensitive ? basePath : basePath.toLowerCase();
-    String filePathToCompare = caseSensitive ? filePath : filePath.toLowerCase();
-    if (basePathToCompare.equals(ensureEnds(filePathToCompare, separator))) return ".";
+    if (basePath.equals(ensureEnds(filePath, separator))) return ".";
     int len = 0;
     int lastSeparatorIndex = 0; // need this for cases like this: base="/temp/abc/base" and file="/temp/ab"
-    while (len < filePath.length() && len < basePath.length() && filePathToCompare.charAt(len) == basePathToCompare.charAt(len)) {
+    final CharComparingStrategy charComparingStrategy = caseSensitive? CharComparingStrategy.IDENTITY : CharComparingStrategy.CASE_INSENSITIVE;
+    while (len < filePath.length() && len < basePath.length() && charComparingStrategy.charsEqual(filePath.charAt(len), basePath.charAt(len))) {
       if (basePath.charAt(len) == separator) {
         lastSeparatorIndex = len;
       }
@@ -798,4 +794,21 @@ public class FileUtilRt {
       return 2500 * KILOBYTE;
     }
   }
+
+  private interface CharComparingStrategy {
+    CharComparingStrategy IDENTITY = new CharComparingStrategy() {
+      @Override
+      public boolean charsEqual(char ch1, char ch2) {
+        return ch1 == ch2;
+      }
+    };
+    CharComparingStrategy CASE_INSENSITIVE = new CharComparingStrategy() {
+      @Override
+      public boolean charsEqual(char ch1, char ch2) {
+        return StringUtilRt.charsEqualIgnoreCase(ch1, ch2);
+      }
+    };
+
+    boolean charsEqual(char ch1, char ch2);
+  }
 }