diff --git a/libc/include/net/ethernet.h b/libc/include/net/ethernet.h
index b1b88dd..47858b3 100644
--- a/libc/include/net/ethernet.h
+++ b/libc/include/net/ethernet.h
@@ -25,8 +25,11 @@
  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  */
+
 #ifndef _NET_ETHERNET_H_
-#define _NET_IF_ETHERNET_H_
+#define _NET_ETHERNET_H_
+
 #include <linux/if_ether.h>
 #include <net/if_ether.h>
-#endif /* !_NET_ETHERNET_H_ */
+
+#endif
diff --git a/libc/include/net/if.h b/libc/include/net/if.h
index f36f37e..0efbf7f 100644
--- a/libc/include/net/if.h
+++ b/libc/include/net/if.h
@@ -26,9 +26,13 @@
  * SUCH DAMAGE.
  */
 
+#ifndef _NET_IF_H_
+#define _NET_IF_H_
+
 #include <sys/socket.h>
 #include <linux/if.h>
 #include <sys/cdefs.h>
+
 #ifndef IF_NAMESIZE
 #define IF_NAMESIZE IFNAMSIZ
 #endif
@@ -42,3 +46,5 @@
 extern char*        if_indextoname(unsigned ifindex, char *ifname);
 
 __END_DECLS
+
+#endif
diff --git a/libc/include/net/route.h b/libc/include/net/route.h
index d26bfc9..326fbe7 100644
--- a/libc/include/net/route.h
+++ b/libc/include/net/route.h
@@ -1,2 +1,37 @@
+/*
+ * Copyright (C) 2014 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#ifndef _NET_ROUTE_H_
+#define _NET_ROUTE_H_
+
+#include <sys/socket.h>
 #include <linux/route.h>
+#include <linux/in6.h>
 #include <linux/ipv6_route.h>
+
+#endif
diff --git a/tests/dlfcn_test.cpp b/tests/dlfcn_test.cpp
index c988d29..6fdfdc7 100644
--- a/tests/dlfcn_test.cpp
+++ b/tests/dlfcn_test.cpp
@@ -819,7 +819,7 @@
 
 TEST(dlfcn, dlsym_weak_func) {
   dlerror();
-  void* handle = dlopen("libtest_dlsym_weak_func.so",RTLD_NOW);
+  void* handle = dlopen("libtest_dlsym_weak_func.so", RTLD_NOW);
   ASSERT_TRUE(handle != NULL);
 
   int (*weak_func)();
@@ -829,6 +829,18 @@
   dlclose(handle);
 }
 
+TEST(dlfcn, dlopen_undefined_weak_func) {
+  test_isolated([] {
+    void* handle = dlopen("libtest_dlopen_weak_undefined_func.so", RTLD_NOW);
+    ASSERT_TRUE(handle != nullptr) << dlerror();
+    int (*weak_func)();
+    weak_func = reinterpret_cast<int (*)()>(dlsym(handle, "use_weak_undefined_func"));
+    ASSERT_TRUE(weak_func != nullptr) << dlerror();
+    EXPECT_EQ(6551, weak_func());
+    dlclose(handle);
+  });
+}
+
 TEST(dlfcn, dlopen_symlink) {
   void* handle1 = dlopen("libdlext_test.so", RTLD_NOW);
   void* handle2 = dlopen("libdlext_test_v2.so", RTLD_NOW);
diff --git a/tests/libs/Android.mk b/tests/libs/Android.mk
index e4620f5..50d96b2 100644
--- a/tests/libs/Android.mk
+++ b/tests/libs/Android.mk
@@ -358,3 +358,12 @@
 
 module := libtest_dlsym_weak_func
 include $(LOCAL_PATH)/Android.build.testlib.mk
+
+# -----------------------------------------------------------------------------
+# Library with weak undefined function
+# -----------------------------------------------------------------------------
+libtest_dlopen_weak_undefined_func_src_files := \
+    dlopen_weak_undefined.cpp
+
+module := libtest_dlopen_weak_undefined_func
+include $(LOCAL_PATH)/Android.build.testlib.mk
diff --git a/tests/libs/dlopen_weak_undefined.cpp b/tests/libs/dlopen_weak_undefined.cpp
new file mode 100644
index 0000000..599a52e
--- /dev/null
+++ b/tests/libs/dlopen_weak_undefined.cpp
@@ -0,0 +1,25 @@
+/*
+ * Copyright (C) 2014 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+extern "C" int __attribute__((weak)) weak_undefined_func();
+
+extern "C" int use_weak_undefined_func() {
+  if (weak_undefined_func) {
+    return weak_undefined_func();
+  } else {
+    return 6551;
+  }
+}