diff --git a/teavm-classlib/src/main/java/org/teavm/classlib/java/lang/TString.java b/teavm-classlib/src/main/java/org/teavm/classlib/java/lang/TString.java
index efadef73b..6ae456a0e 100644
--- a/teavm-classlib/src/main/java/org/teavm/classlib/java/lang/TString.java
+++ b/teavm-classlib/src/main/java/org/teavm/classlib/java/lang/TString.java
@@ -307,7 +307,7 @@ public class TString extends TObject implements TSerializable, TComparable<TStri
     public int indexOf(TString str, int fromIndex) {
         int toIndex = length() - str.length();
         outer:
-        for (int i = fromIndex; i < toIndex; ++i) {
+        for (int i = fromIndex; i <= toIndex; ++i) {
             for (int j = 0; j < str.length(); ++j) {
                 if (charAt(i + j) != str.charAt(j)) {
                     continue outer;
diff --git a/teavm-classlib/src/test/java/org/teavm/classlib/java/lang/StringTest.java b/teavm-classlib/src/test/java/org/teavm/classlib/java/lang/StringTest.java
index 5e51dfb65..80ef31a9a 100644
--- a/teavm-classlib/src/test/java/org/teavm/classlib/java/lang/StringTest.java
+++ b/teavm-classlib/src/test/java/org/teavm/classlib/java/lang/StringTest.java
@@ -160,6 +160,7 @@ public class StringTest {
     @Test
     public void findsString() {
         assertEquals(1, "abcdbcd".indexOf("bc"));
+        assertEquals(3, "abcdbcd".indexOf("dbcd"));
         assertEquals(-1, "abcdbcd".indexOf("bb"));
     }