diff --git a/binding/java/src/main/java/org/lionsoul/ip2region/DbSearcher.java b/binding/java/src/main/java/org/lionsoul/ip2region/DbSearcher.java
index 5bc8e8f..b7721ef 100644
--- a/binding/java/src/main/java/org/lionsoul/ip2region/DbSearcher.java
+++ b/binding/java/src/main/java/org/lionsoul/ip2region/DbSearcher.java
@@ -82,7 +82,7 @@ public class DbSearcher
         int l = 0, h = totalIndexBlocks;
         long sip, eip, dataptr = 0;
         while ( l <= h ) {
-            int m = (l + h) >> 1;
+            int m = Util.mean(l, h);
             int p = (int)(firstIndexPtr + m * blen);
             
             sip = Util.getIntLong(dbBinStr, p);
@@ -194,7 +194,7 @@ public class DbSearcher
         
         int l = 0, h = headerLength, sptr = 0, eptr = 0;
         while ( l <= h ) {
-            int m = (l + h) >> 1;
+            int m = Util.mean(l, h);
             
             //perfetc matched, just return it
             if ( ip == HeaderSip[m] ) {
@@ -247,7 +247,7 @@ public class DbSearcher
         l = 0; h = blockLen / blen;
         long sip, eip, dataptr = 0;
         while ( l <= h ) {
-            int m = (l + h) >> 1;
+            int m = Util.mean(l, h);
             int p = m * blen;
             sip = Util.getIntLong(iBuffer, p);
             if ( ip < sip ) {
@@ -316,7 +316,7 @@ public class DbSearcher
         byte[] buffer = new byte[blen];
         long sip, eip, dataptr = 0;
         while ( l <= h ) {
-            int m = (l + h) >> 1;
+            int m = Util.mean(l, h);
             raf.seek(firstIndexPtr + m * blen);    //set the file pointer
             raf.readFully(buffer, 0, buffer.length);
             sip = Util.getIntLong(buffer, 0);
diff --git a/binding/java/src/main/java/org/lionsoul/ip2region/Util.java b/binding/java/src/main/java/org/lionsoul/ip2region/Util.java
index f94d3ee..0044e18 100644
--- a/binding/java/src/main/java/org/lionsoul/ip2region/Util.java
+++ b/binding/java/src/main/java/org/lionsoul/ip2region/Util.java
@@ -140,4 +140,19 @@ public class Util
         
         return true;
     }
+
+    /**
+     * Returns the arithmetic mean of {@code x} and {@code y}, rounded towards
+     * negative infinity. This method is overflow resilient.
+     *
+     * code from guava 14.0
+     * com.google.common.math.IntMath.mean(int x, int y)
+     *
+     */
+    public static int mean(int x, int y) {
+        // Efficient method for computing the arithmetic mean.
+        // The alternative (x + y) / 2 fails for large values.
+        // The alternative (x + y) >>> 1 fails for negative values.
+        return (x & y) + ((x ^ y) >> 1);
+    }
 }