diff --git a/libc/include/sys/un.h b/libc/include/sys/un.h
index 3e1c429..03ef5e4 100644
--- a/libc/include/sys/un.h
+++ b/libc/include/sys/un.h
@@ -33,4 +33,9 @@
 #include <linux/un.h>
 #include <sys/cdefs.h>
 
+#if defined(__USE_BSD) || defined(__USE_GNU)
+#include <string.h>
+#define SUN_LEN(__ptr) (offsetof(struct sockaddr_un, sun_path) + strlen((__ptr)->sun_path))
+#endif
+
 #endif
diff --git a/linker/linker_phdr.cpp b/linker/linker_phdr.cpp
index b24be92..54354a8 100644
--- a/linker/linker_phdr.cpp
+++ b/linker/linker_phdr.cpp
@@ -213,7 +213,8 @@
 
 bool ElfReader::VerifyElfHeader() {
   if (memcmp(header_.e_ident, ELFMAG, SELFMAG) != 0) {
-    DL_ERR("\"%s\" has bad ELF magic", name_.c_str());
+    DL_ERR("\"%s\" has bad ELF magic: %02x%02x%02x%02x", name_.c_str(),
+           header_.e_ident[0], header_.e_ident[1], header_.e_ident[2], header_.e_ident[3]);
     return false;
   }
 
diff --git a/tests/Android.bp b/tests/Android.bp
index 00f2856..b504fa1 100644
--- a/tests/Android.bp
+++ b/tests/Android.bp
@@ -167,6 +167,7 @@
         "sys_ttydefaults_test.cpp",
         "sys_types_test.cpp",
         "sys_uio_test.cpp",
+        "sys_un_test.cpp",
         "sys_vfs_test.cpp",
         "sys_xattr_test.cpp",
         "system_properties_test.cpp",
diff --git a/tests/dlext_test.cpp b/tests/dlext_test.cpp
index ec27932..1e3d9c8 100644
--- a/tests/dlext_test.cpp
+++ b/tests/dlext_test.cpp
@@ -173,7 +173,7 @@
   extinfo.library_fd_offset = 0;
   handle_ = android_dlopen_ext("libname_ignored", RTLD_NOW, &extinfo);
   ASSERT_TRUE(handle_ == nullptr);
-  ASSERT_EQ("dlopen failed: \"" + lib_path + "\" has bad ELF magic", dlerror());
+  ASSERT_EQ("dlopen failed: \"" + lib_path + "\" has bad ELF magic: 504b0304", dlerror());
 
   // Check if dlsym works after unsuccessful dlopen().
   // Supply non-exiting one to make linker visit every soinfo.
diff --git a/tests/sys_un_test.cpp b/tests/sys_un_test.cpp
new file mode 100644
index 0000000..08a4d0f
--- /dev/null
+++ b/tests/sys_un_test.cpp
@@ -0,0 +1,27 @@
+/*
+ * Copyright (C) 2018 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.
+ */
+
+#include <sys/un.h>
+
+#include <string.h>
+#include <gtest/gtest.h>
+
+TEST(sys_un, SUN_LEN_macro) {
+  sockaddr_un sun = {};
+  sun.sun_family = 1;
+  strcpy(sun.sun_path, "hello");
+  ASSERT_EQ(2U + strlen("hello"), SUN_LEN(&sun));
+}