diff --git a/transport-native-epoll/pom.xml b/transport-native-epoll/pom.xml
index c5b0c84604..20ccbea8ac 100644
--- a/transport-native-epoll/pom.xml
+++ b/transport-native-epoll/pom.xml
@@ -186,7 +186,7 @@
               <value>${linux.sendmmsg.support}${glibc.sendmmsg.support}</value>
               <!-- If glibc and linux kernel are both not sufficient...then define the CFLAGS -->
               <regex>.*IO_NETTY_SENDMSSG_NOT_FOUND.*</regex>
-              <replacement>CFLAGS=-O3 -DIO_NETTY_SENDMMSG_NOT_FOUND</replacement>
+              <replacement>CFLAGS=-O3 -DIO_NETTY_SENDMMSG_NOT_FOUND -Werror</replacement>
               <failIfNoMatch>false</failIfNoMatch>
             </configuration>
           </execution>
@@ -202,7 +202,7 @@
               <value>${jni.compiler.args}</value>
               <!-- If glibc and linux kernel are both not sufficient...then define the CFLAGS -->
               <regex>^((?!CFLAGS=).)*$</regex>
-              <replacement>CFLAGS=-O3</replacement>
+              <replacement>CFLAGS=-O3 -Werror</replacement>
               <failIfNoMatch>false</failIfNoMatch>
             </configuration>
           </execution>
diff --git a/transport-native-epoll/src/main/c/io_netty_channel_epoll_Native.c b/transport-native-epoll/src/main/c/io_netty_channel_epoll_Native.c
index 863ce85dc6..59ee8f741a 100644
--- a/transport-native-epoll/src/main/c/io_netty_channel_epoll_Native.c
+++ b/transport-native-epoll/src/main/c/io_netty_channel_epoll_Native.c
@@ -33,6 +33,7 @@
 #include <sys/utsname.h>
 #include <stddef.h>
 #include <limits.h>
+#include <inttypes.h>
 #include "io_netty_channel_epoll_Native.h"
 #include "exception_helper.h"
 
@@ -1057,6 +1058,8 @@ JNIEXPORT jint JNICALL Java_io_netty_channel_epoll_Native_shutdown0(JNIEnv* env,
         mode = SHUT_RD;
     } else if (write) {
         mode = SHUT_WR;
+    } else {
+        return -EINVAL;
     }
     if (shutdown(fd, mode) < 0) {
         return -errno;
@@ -1097,12 +1100,14 @@ JNIEXPORT jint JNICALL Java_io_netty_channel_epoll_Native_bind(JNIEnv* env, jcla
     if (bind(fd, (struct sockaddr*) &addr, sizeof(addr)) == -1) {
         return -errno;
     }
+    return 0;
 }
 
 JNIEXPORT jint JNICALL Java_io_netty_channel_epoll_Native_listen0(JNIEnv* env, jclass clazz, jint fd, jint backlog) {
     if (listen(fd, backlog) == -1) {
         return -errno;
     }
+    return 0;
 }
 
 JNIEXPORT jint JNICALL Java_io_netty_channel_epoll_Native_connect(JNIEnv* env, jclass clazz, jint fd, jbyteArray address, jint scopeId, jint port) {
@@ -1560,7 +1565,7 @@ JNIEXPORT jint JNICALL Java_io_netty_channel_epoll_Native_socketDomain(JNIEnv* e
 
 // macro to calculate the length of a sockaddr_un struct for a given path length.
 // see sys/un.h#SUN_LEN, this is modified to allow nul bytes
-#define _UNIX_ADDR_LENGTH(path_len) (((struct sockaddr_un *) 0)->sun_path) + path_len
+#define _UNIX_ADDR_LENGTH(path_len) (uintptr_t) (((struct sockaddr_un *) 0)->sun_path) + path_len
 
 JNIEXPORT jint JNICALL Java_io_netty_channel_epoll_Native_bindDomainSocket(JNIEnv* env, jclass clazz, jint fd, jbyteArray socketPath) {
     struct sockaddr_un addr;
@@ -1568,7 +1573,7 @@ JNIEXPORT jint JNICALL Java_io_netty_channel_epoll_Native_bindDomainSocket(JNIEn
     memset(&addr, 0, sizeof(addr));
     addr.sun_family = AF_UNIX;
 
-    const jbyte* socket_path = (*env)->GetByteArrayElements(env, socketPath, 0);
+    jbyte* socket_path = (*env)->GetByteArrayElements(env, socketPath, 0);
     jint socket_path_len = (*env)->GetArrayLength(env, socketPath);
     if (socket_path_len > sizeof(addr.sun_path)) {
         socket_path_len = sizeof(addr.sun_path);
@@ -1595,7 +1600,7 @@ JNIEXPORT jint JNICALL Java_io_netty_channel_epoll_Native_connectDomainSocket(JN
     memset(&addr, 0, sizeof(addr));
     addr.sun_family = AF_UNIX;
 
-    const jbyte* socket_path = (*env)->GetByteArrayElements(env, socketPath, 0);
+    jbyte* socket_path = (*env)->GetByteArrayElements(env, socketPath, 0);
     socket_path_len = (*env)->GetArrayLength(env, socketPath);
     if (socket_path_len > sizeof(addr.sun_path)) {
         socket_path_len = sizeof(addr.sun_path);
@@ -1685,7 +1690,7 @@ JNIEXPORT jint JNICALL Java_io_netty_channel_epoll_Native_sendFd0(JNIEnv* env, j
         iov[0].iov_base = iovecData;
         iov[0].iov_len = sizeof(iovecData);
 
-        size_t res;
+        ssize_t res;
         int err;
         do {
             res = sendmsg(socketFd, &descriptorMessage, 0);
@@ -1758,14 +1763,17 @@ JNIEXPORT jlong JNICALL Java_io_netty_channel_epoll_Native_pipe0(JNIEnv* env, jc
     return (((long) fd[0]) << 32) | (fd[1] & 0xffffffffL);
 }
 
-JNIEXPORT jint JNICALL Java_io_netty_channel_epoll_Native_splice0(JNIEnv* env, jclass clazz, jint fd, jint offIn, jint fdOut, jint offOut, jint len) {
+JNIEXPORT jint JNICALL Java_io_netty_channel_epoll_Native_splice0(JNIEnv* env, jclass clazz, jint fd, jlong offIn, jint fdOut, jlong offOut, jlong len) {
     ssize_t res;
     int err;
-    loff_t off_in = offIn >= 0 ? (loff_t) offIn : NULL;
-    loff_t off_out = offOut >= 0 ? (loff_t) offOut : NULL;
+    loff_t off_in = (loff_t) offIn;
+    loff_t off_out = (loff_t) offOut;
+
+    loff_t* p_off_in = off_in >= 0 ? &off_in : NULL;
+    loff_t* p_off_out = off_in >= 0 ? &off_out : NULL;
 
     do {
-       res = splice(fd, off_in, fdOut, off_out, (size_t) len, SPLICE_F_NONBLOCK | SPLICE_F_MOVE);
+       res = splice(fd, p_off_in, fdOut, p_off_out, (size_t) len, SPLICE_F_NONBLOCK | SPLICE_F_MOVE);
        // keep on splicing if it was interrupted
     } while (res == -1 && ((err = errno) == EINTR));
 
diff --git a/transport-native-epoll/src/main/c/io_netty_channel_epoll_Native.h b/transport-native-epoll/src/main/c/io_netty_channel_epoll_Native.h
index 1e0dd968da..16e88cf92f 100644
--- a/transport-native-epoll/src/main/c/io_netty_channel_epoll_Native.h
+++ b/transport-native-epoll/src/main/c/io_netty_channel_epoll_Native.h
@@ -130,7 +130,7 @@ jint Java_io_netty_channel_epoll_Native_sizeofEpollEvent(JNIEnv* env, jclass cla
 jint Java_io_netty_channel_epoll_Native_offsetofEpollData(JNIEnv* env, jclass clazz);
 
 jlong Java_io_netty_channel_epoll_Native_pipe0(JNIEnv* env, jclass clazz);
-jint Java_io_netty_channel_epoll_Native_splice0(JNIEnv* env, jclass clazz, jint fd, jint offIn, jint fdOut, jint offOut, jint len);
+jint Java_io_netty_channel_epoll_Native_splice0(JNIEnv* env, jclass clazz, jint fd, jlong offIn, jint fdOut, jlong offOut, jlong len);
 
 jint Java_io_netty_channel_epoll_Native_tcpMd5SigMaxKeyLen(JNIEnv* env, jclass clazz);
 void Java_io_netty_channel_epoll_Native_setTcpMd5Sig0(JNIEnv* env, jclass clazz, jint fd, jbyteArray address, jint scopeId, jbyteArray key);
diff --git a/transport-native-epoll/src/main/java/io/netty/channel/epoll/Native.java b/transport-native-epoll/src/main/java/io/netty/channel/epoll/Native.java
index 54d6976952..b1a75e154c 100644
--- a/transport-native-epoll/src/main/java/io/netty/channel/epoll/Native.java
+++ b/transport-native-epoll/src/main/java/io/netty/channel/epoll/Native.java
@@ -205,7 +205,7 @@ public final class Native {
 
     private static native int close0(int fd);
 
-    public static int splice(int fd, int offIn, int fdOut, int offOut, int len) throws IOException {
+    public static int splice(int fd, long offIn, int fdOut, long offOut, long len) throws IOException {
         int res = splice0(fd, offIn, fdOut, offOut, len);
         if (res >= 0) {
             return res;
@@ -213,7 +213,7 @@ public final class Native {
         return ioResult("splice", res, CONNECTION_RESET_EXCEPTION_SPLICE);
     }
 
-    private static native int splice0(int fd, int offIn, int fdOut, int offOut, int len);
+    private static native int splice0(int fd, long offIn, int fdOut, long offOut, long len);
 
     public static long pipe() throws IOException {
         long res = pipe0();