diff --git a/classlib/src/main/java/org/teavm/classlib/java/lang/TAbstractStringBuilder.java b/classlib/src/main/java/org/teavm/classlib/java/lang/TAbstractStringBuilder.java
index 4b261f748..b2bda3d00 100644
--- a/classlib/src/main/java/org/teavm/classlib/java/lang/TAbstractStringBuilder.java
+++ b/classlib/src/main/java/org/teavm/classlib/java/lang/TAbstractStringBuilder.java
@@ -668,12 +668,15 @@ class TAbstractStringBuilder implements TSerializable, TCharSequence {
     }
 
     public TAbstractStringBuilder delete(int start, int end) {
-        if (start > end || start > length) {
+        if (start < 0 || start > end || start > length) {
             throw new TStringIndexOutOfBoundsException();
         }
         if (start == end) {
             return this;
         }
+        if (end > length) {
+            end = length;
+        }
         int sz = length - end;
         length -= end - start;
         for (int i = 0; i < sz; ++i) {
@@ -683,6 +686,12 @@ class TAbstractStringBuilder implements TSerializable, TCharSequence {
     }
 
     public TAbstractStringBuilder replace(int start, int end, TString str) {
+        if (start < 0 || start > end || start > length) {
+            throw new TStringIndexOutOfBoundsException();
+        }
+        if (end > length) {
+            end = length;
+        }
         int oldSize = end - start;
         if (str.length() > oldSize) {
             insertSpace(end, start + str.length());
diff --git a/tests/src/test/java/org/teavm/classlib/java/lang/StringBuilderTest.java b/tests/src/test/java/org/teavm/classlib/java/lang/StringBuilderTest.java
index dfabd189c..12e7a2d58 100644
--- a/tests/src/test/java/org/teavm/classlib/java/lang/StringBuilderTest.java
+++ b/tests/src/test/java/org/teavm/classlib/java/lang/StringBuilderTest.java
@@ -16,6 +16,7 @@
 package org.teavm.classlib.java.lang;
 
 import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.fail;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.teavm.junit.TeaVMTestRunner;
@@ -203,8 +204,8 @@ public class StringBuilderTest {
     }
 
     @Test
-    public void substringWithUpperBoundAtEndWorks() {
-        assertEquals("23", "123".substring(1, 3));
+    public void substringWorks() {
+        assertEquals("23", new StringBuilder("123").substring(1, 3));
     }
 
     @Test
@@ -216,4 +217,52 @@ public class StringBuilderTest {
         assertEquals(0, sb.indexOf("12345"));
         assertEquals(0, sb.indexOf("123"));
     }
+
+    @Test
+    public void delete() {
+        StringBuilder sb = new StringBuilder("abcdef");
+        try {
+            sb.delete(-1, 3);
+            fail();
+        } catch (StringIndexOutOfBoundsException e) {
+            // ok
+        }
+        try {
+            sb.delete(7, 8);
+            fail();
+        } catch (StringIndexOutOfBoundsException e) {
+            // ok
+        }
+        sb.delete(6, 50);
+        assertEquals("abcdef", sb.toString());
+        sb.delete(5, 50);
+        assertEquals("abcde", sb.toString());
+        sb.delete(1, 4);
+        assertEquals("ae", sb.toString());
+    }
+
+    @Test
+    public void replace() {
+        StringBuilder sb = new StringBuilder("abcdef");
+        try {
+            sb.replace(-1, 3, "h");
+            fail();
+        } catch (StringIndexOutOfBoundsException e) {
+            // ok
+        }
+        try {
+            sb.replace(7, 8, "h");
+            fail();
+        } catch (StringIndexOutOfBoundsException e) {
+            // ok
+        }
+        sb.replace(6, 50, "g");
+        assertEquals("abcdefg", sb.toString());
+        sb.replace(6, 50, "h");
+        assertEquals("abcdefh", sb.toString());
+        sb.replace(1, 6, "g");
+        assertEquals("agh", sb.toString());
+        sb.replace(1, 1, "bc");
+        assertEquals("abcgh", sb.toString());
+    }
 }