diff --git a/libjava/ChangeLog b/libjava/ChangeLog
index 079c8e2a2088..385e26d8cdd3 100644
--- a/libjava/ChangeLog
+++ b/libjava/ChangeLog
@@ -1,3 +1,9 @@
+2007-05-07  Ian Lance Taylor  <iant@google.com>
+
+	PR java/31842
+	* java/lang/natString.cc (_Jv_FormatInt): Avoid undefined signed
+	overflow.
+
 2007-05-07  Keith Seitz  <keiths@redhat.com>
 
 	* classpath/lib/gnu/classpath/jdwp/Jdwp.class: Regenerate.
diff --git a/libjava/java/lang/natString.cc b/libjava/java/lang/natString.cc
index 39590a3e4e07..f177c23ccc47 100644
--- a/libjava/java/lang/natString.cc
+++ b/libjava/java/lang/natString.cc
@@ -371,11 +371,11 @@ _Jv_FormatInt (jchar* bufend, jint num)
   if (num < 0)
     {
       isNeg = true;
-      num = -(num);
-      if (num < 0)
+      if (num != (jint) -2147483648U)
+	num = -(num);
+      else
 	{
-	  // Must be MIN_VALUE, so handle this special case.
-	  // FIXME use 'unsigned jint' for num.
+	  // Handle special case of MIN_VALUE.
 	  *--ptr = '8';
 	  num = 214748364;
 	}