diff --git a/src/main/java/org/xerial/snappy/Snappy.java b/src/main/java/org/xerial/snappy/Snappy.java
index 4c62d5a..ffb004d 100755
--- a/src/main/java/org/xerial/snappy/Snappy.java
+++ b/src/main/java/org/xerial/snappy/Snappy.java
@@ -47,13 +47,16 @@ public class Snappy
      * @param compressed
      *            output compressed data to buffer[pos()..]
      * @return byte size of the compressed data.
+     * 
+     * @throws SnappyError
+     *             when the input is not a direct buffer
      */
     public static int compress(ByteBuffer uncompressed, ByteBuffer compressed) {
 
         if (!uncompressed.isDirect())
-            throw new IllegalArgumentException("input is not a direct buffer");
+            throw new SnappyError(SnappyErrorCode.NOT_A_DIRECT_BUFFER, "input is not a direct buffer");
         if (!compressed.isDirect())
-            throw new IllegalArgumentException("destination is not a direct buffer");
+            throw new SnappyError(SnappyErrorCode.NOT_A_DIRECT_BUFFER, "destination is not a direct buffer");
 
         // input: uncompressed[pos(), limit())
         // output: compressed
@@ -77,13 +80,17 @@ public class Snappy
      *            output the uncompressed data to buffer[pot())
      * @return uncompressed data size
      * 
+     * @throws SnappyException
+     *             when failed to uncompress the given input
+     * @throws SnappyError
+     *             when the input is not a direct buffer
      */
     public static int uncompress(ByteBuffer compressed, ByteBuffer uncompressed) throws SnappyException {
 
         if (!compressed.isDirect())
-            throw new IllegalArgumentException("input is not a direct buffer");
+            throw new SnappyError(SnappyErrorCode.NOT_A_DIRECT_BUFFER, "input is not a direct buffer");
         if (!uncompressed.isDirect())
-            throw new IllegalArgumentException("destination is not a direct buffer");
+            throw new SnappyError(SnappyErrorCode.NOT_A_DIRECT_BUFFER, "destination is not a direct buffer");
 
         int cPos = compressed.position();
         int cLen = compressed.remaining();
@@ -102,11 +109,15 @@ public class Snappy
      * 
      * @param compressed
      *            data [pos() ... limit())
-     * @return
+     * @return uncompressed byte length of the given input
+     * @throws SnappyException
+     *             when failed to uncompress the given input
+     * @throws SnappyError
+     *             when the input is not a direct buffer
      */
     public static int uncompressedLength(ByteBuffer compressed) throws SnappyException {
         if (!compressed.isDirect())
-            throw new IllegalArgumentException("input is not a direct buffer");
+            throw new SnappyError(SnappyErrorCode.NOT_A_DIRECT_BUFFER, "input is not a direct buffer");
 
         return SnappyNative.uncompressedLength(compressed, compressed.position(), compressed.remaining());
     }
diff --git a/src/main/java/org/xerial/snappy/SnappyError.java b/src/main/java/org/xerial/snappy/SnappyError.java
index 124281a..b377470 100755
--- a/src/main/java/org/xerial/snappy/SnappyError.java
+++ b/src/main/java/org/xerial/snappy/SnappyError.java
@@ -43,4 +43,10 @@ public class SnappyError extends Error
         super(e);
         this.errorCode = code;
     }
+
+    public SnappyError(SnappyErrorCode code, String message) {
+        super(message);
+        this.errorCode = code;
+    }
+
 }
diff --git a/src/main/java/org/xerial/snappy/SnappyErrorCode.java b/src/main/java/org/xerial/snappy/SnappyErrorCode.java
index a1de884..2798fde 100755
--- a/src/main/java/org/xerial/snappy/SnappyErrorCode.java
+++ b/src/main/java/org/xerial/snappy/SnappyErrorCode.java
@@ -32,7 +32,7 @@ package org.xerial.snappy;
  */
 public enum SnappyErrorCode {
 
-    UNKNOWN(0), FAILED_TO_LOAD_NATIVE_LIBRARY(1), PARSING_ERROR(2);
+    UNKNOWN(0), FAILED_TO_LOAD_NATIVE_LIBRARY(1), PARSING_ERROR(2), NOT_A_DIRECT_BUFFER(3);
 
     public final int id;
 
diff --git a/src/test/java/org/xerial/snappy/SnappyTest.java b/src/test/java/org/xerial/snappy/SnappyTest.java
index ce00f29..17899a8 100755
--- a/src/test/java/org/xerial/snappy/SnappyTest.java
+++ b/src/test/java/org/xerial/snappy/SnappyTest.java
@@ -28,6 +28,7 @@ import static org.junit.Assert.*;
 
 import java.nio.ByteBuffer;
 
+import org.junit.Assert;
 import org.junit.Test;
 import org.xerial.util.log.Logger;
 
@@ -51,8 +52,8 @@ public class SnappyTest
             ByteBuffer dest = ByteBuffer.allocate(1024);
             int maxCompressedLen = Snappy.compress(src, dest);
         }
-        catch (IllegalArgumentException e) {
-            // detected non-direct buffer. OK
+        catch (SnappyError e) {
+            Assert.assertTrue(e.errorCode == SnappyErrorCode.NOT_A_DIRECT_BUFFER);
             return;
         }
 
@@ -67,7 +68,8 @@ public class SnappyTest
         for (int i = 0; i < 20; ++i) {
             s.append("Hello world!");
         }
-        byte[] orig = s.toString().getBytes();
+        String origStr = s.toString();
+        byte[] orig = origStr.getBytes();
         int BUFFER_SIZE = orig.length;
         ByteBuffer src = ByteBuffer.allocateDirect(orig.length * 2);
         src.put(orig);
@@ -89,5 +91,7 @@ public class SnappyTest
         extract.get(b);
         String decompressed = new String(b);
         _logger.info(decompressed);
+
+        assertEquals(origStr, decompressed);
     }
 }