diff --git a/core/src/main/java/hudson/MarkupText.java b/core/src/main/java/hudson/MarkupText.java
index 138dc6202d..1e46a384ca 100644
--- a/core/src/main/java/hudson/MarkupText.java
+++ b/core/src/main/java/hudson/MarkupText.java
@@ -98,7 +98,7 @@ public class MarkupText extends AbstractMarkupText {
         @Override
         public SubText subText(int start, int end) {
             return MarkupText.this.subText(this.start+start,
-                    end<0 ? this.end+1+end : this.end+end);
+                    end<0 ? this.end+1+end : this.start+end);
         }
 
         @Override
diff --git a/core/src/test/java/hudson/MarkupTextTest.java b/core/src/test/java/hudson/MarkupTextTest.java
index 1b5455cf94..06a63e837e 100644
--- a/core/src/test/java/hudson/MarkupTextTest.java
+++ b/core/src/test/java/hudson/MarkupTextTest.java
@@ -28,8 +28,6 @@ import hudson.MarkupText.SubText;
 
 import java.util.List;
 import java.util.regex.Pattern;
-import java.net.URL;
-import java.net.MalformedURLException;
 
 /**
  * @author Kohsuke Kawaguchi
@@ -101,5 +99,20 @@ public class MarkupTextTest extends TestCase {
         assertEquals("Line<hr/>\n2   &amp; 3\n&lt;End>\n", text.toString(true));
     }
 
+    /* @Bug(6252) */
+    public void testSubTextSubText() {
+        MarkupText text = new MarkupText("abcdefgh");
+        SubText sub = text.subText(2, 7);
+        assertEquals("cdefg", sub.getText());
+        sub = sub.subText(1, 4);
+        assertEquals("def", sub.getText());
+
+        // test negative end
+        sub = text.subText(2, -3);
+        assertEquals("cdef", sub.getText());
+        sub = sub.subText(1, -2);
+        assertEquals("de", sub.getText());
+    }
+
     private static final Pattern pattern = Pattern.compile("issue #([0-9]+)");
 }