diff --git a/codec-http/src/main/java/io/netty/handler/codec/http/multipart/HttpPostStandardRequestDecoder.java b/codec-http/src/main/java/io/netty/handler/codec/http/multipart/HttpPostStandardRequestDecoder.java
index 52133c428f..085609a3b4 100644
--- a/codec-http/src/main/java/io/netty/handler/codec/http/multipart/HttpPostStandardRequestDecoder.java
+++ b/codec-http/src/main/java/io/netty/handler/codec/http/multipart/HttpPostStandardRequestDecoder.java
@@ -633,6 +633,10 @@ public class HttpPostStandardRequestDecoder implements InterfaceHttpPostRequestD
             // error while decoding
             undecodedChunk.readerIndex(firstpos);
             throw new ErrorDataDecoderException(e);
+        } catch (IllegalArgumentException e) {
+            // error while decoding
+            undecodedChunk.readerIndex(firstpos);
+            throw new ErrorDataDecoderException(e);
         }
     }
 
diff --git a/codec-http/src/test/java/io/netty/handler/codec/http/multipart/HttpPostRequestDecoderTest.java b/codec-http/src/test/java/io/netty/handler/codec/http/multipart/HttpPostRequestDecoderTest.java
index 687745584e..28ef7a0998 100644
--- a/codec-http/src/test/java/io/netty/handler/codec/http/multipart/HttpPostRequestDecoderTest.java
+++ b/codec-http/src/test/java/io/netty/handler/codec/http/multipart/HttpPostRequestDecoderTest.java
@@ -23,6 +23,7 @@ import io.netty.handler.codec.DecoderResult;
 import io.netty.handler.codec.http.DefaultFullHttpRequest;
 import io.netty.handler.codec.http.DefaultHttpContent;
 import io.netty.handler.codec.http.DefaultHttpRequest;
+import io.netty.handler.codec.http.DefaultLastHttpContent;
 import io.netty.handler.codec.http.HttpContent;
 import io.netty.handler.codec.http.HttpHeaderNames;
 import io.netty.handler.codec.http.HttpHeaderValues;
@@ -474,4 +475,21 @@ public class HttpPostRequestDecoderTest {
             req.release();
         }
     }
+
+    @Test
+    public void testFormEncodeIncorrect() throws Exception {
+        LastHttpContent content = new DefaultLastHttpContent(
+                Unpooled.copiedBuffer("project=netty&&project=netty", CharsetUtil.US_ASCII));
+        DefaultHttpRequest req = new DefaultHttpRequest(HttpVersion.HTTP_1_1, HttpMethod.POST, "/");
+        HttpPostRequestDecoder decoder = new HttpPostRequestDecoder(req);
+        try {
+            decoder.offer(content);
+            fail();
+        } catch (HttpPostRequestDecoder.ErrorDataDecoderException e) {
+            assertTrue(e.getCause() instanceof IllegalArgumentException);
+        } finally {
+            decoder.destroy();
+            content.release();
+        }
+    }
 }