diff --git a/classlib/src/main/java/org/teavm/classlib/java/lang/TCharacter.java b/classlib/src/main/java/org/teavm/classlib/java/lang/TCharacter.java
index b96d20191..87ac35aac 100644
--- a/classlib/src/main/java/org/teavm/classlib/java/lang/TCharacter.java
+++ b/classlib/src/main/java/org/teavm/classlib/java/lang/TCharacter.java
@@ -363,7 +363,7 @@ public class TCharacter extends TObject implements TComparable<TCharacter> {
     }
 
     public static char forDigit(int digit, int radix) {
-        if (radix < MIN_RADIX || radix > MAX_RADIX || digit >= radix) {
+        if (radix < MIN_RADIX || radix > MAX_RADIX || digit < 0 || digit >= radix) {
             return '\0';
         }
         return digit < 10 ? (char) ('0' + digit) : (char) ('a' + digit - 10);
diff --git a/tests/src/test/java/org/teavm/classlib/java/lang/CharacterTest.java b/tests/src/test/java/org/teavm/classlib/java/lang/CharacterTest.java
index 63938fefa..82d8637e2 100644
--- a/tests/src/test/java/org/teavm/classlib/java/lang/CharacterTest.java
+++ b/tests/src/test/java/org/teavm/classlib/java/lang/CharacterTest.java
@@ -77,4 +77,15 @@ public class CharacterTest {
         assertEquals((char) 12405, Character.reverseBytes((char) 30000));
         assertEquals((char) -12150, Character.reverseBytes((char) -30000));
     }
+
+    @Test
+    public void characterForDigit() {
+        assertEquals('\0', Character.forDigit(-1, 5));
+        assertEquals('\0', Character.forDigit(6, 5));
+        assertEquals('\0', Character.forDigit(1, 1));
+        assertEquals('\0', Character.forDigit(1, 37));
+        assertEquals('a', Character.forDigit(10, 11));
+        assertEquals('\0', Character.forDigit(10, 10));
+        assertEquals('5', Character.forDigit(5, 6));
+    }
 }