diff --git a/libc/Android.mk b/libc/Android.mk
index c47cc6722..3c387d2e1 100644
--- a/libc/Android.mk
+++ b/libc/Android.mk
@@ -238,7 +238,8 @@ libc_bionic_src_files := \
     bionic/brk.cpp \
     bionic/dirent.cpp \
     bionic/__errno.c \
-    bionic/eventfd.cpp \
+    bionic/eventfd_read.cpp \
+    bionic/eventfd_write.cpp \
     bionic/__fgets_chk.cpp \
     bionic/getauxval.cpp \
     bionic/getcwd.cpp \
diff --git a/libc/bionic/eventfd.cpp b/libc/bionic/eventfd_read.cpp
similarity index 75%
rename from libc/bionic/eventfd.cpp
rename to libc/bionic/eventfd_read.cpp
index fc7a6b9b6..50e73fd54 100644
--- a/libc/bionic/eventfd.cpp
+++ b/libc/bionic/eventfd_read.cpp
@@ -29,25 +29,6 @@
 #include <sys/eventfd.h>
 #include <unistd.h>
 
-/* We duplicate the GLibc error semantics, which are poorly defined
- * if the read() or write() does not return the proper number of bytes.
- */
-int eventfd_read(int fd, eventfd_t *counter)
-{
-    int ret = read(fd, counter, sizeof(*counter));
-
-    if (ret == sizeof(*counter))
-        return 0;
-
-    return -1;
-}
-
-int eventfd_write(int fd, eventfd_t counter)
-{
-    int ret = write(fd, &counter, sizeof(counter));
-
-    if (ret == sizeof(counter))
-        return 0;
-
-    return -1;
+int eventfd_read(int fd, eventfd_t* value) {
+  return (read(fd, value, sizeof(*value)) == sizeof(*value)) ? 0 : -1;
 }
diff --git a/libc/bionic/eventfd_write.cpp b/libc/bionic/eventfd_write.cpp
new file mode 100644
index 000000000..3c3d3f1cc
--- /dev/null
+++ b/libc/bionic/eventfd_write.cpp
@@ -0,0 +1,34 @@
+/*
+ * Copyright (C) 2010 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.
+ */
+
+#include <sys/eventfd.h>
+#include <unistd.h>
+
+int eventfd_write(int fd, eventfd_t value) {
+  return (write(fd, &value, sizeof(value)) == sizeof(value)) ? 0 : -1;
+}
diff --git a/libc/include/sys/eventfd.h b/libc/include/sys/eventfd.h
index 19244a5d7..ec84e27b7 100644
--- a/libc/include/sys/eventfd.h
+++ b/libc/include/sys/eventfd.h
@@ -33,17 +33,16 @@
 
 __BEGIN_DECLS
 
-#define  EFD_CLOEXEC   O_CLOEXEC
-#define  EFD_NONBLOCK  O_NONBLOCK
+#define EFD_CLOEXEC O_CLOEXEC
+#define EFD_NONBLOCK O_NONBLOCK
 
 /* type of event counter */
-typedef uint64_t  eventfd_t;
+typedef uint64_t eventfd_t;
 
-extern int eventfd(unsigned int initval, int flags);
+extern int eventfd(unsigned int initial_value, int flags);
 
-/* Compatibility with GLibc */
-extern int eventfd_read(int fd, eventfd_t *counter);
-extern int eventfd_write(int fd, const eventfd_t counter);
+extern int eventfd_read(int fd, eventfd_t* value);
+extern int eventfd_write(int fd, eventfd_t value);
 
 __END_DECLS
 
diff --git a/tests/Android.mk b/tests/Android.mk
index 491b13c15..dee5e3311 100644
--- a/tests/Android.mk
+++ b/tests/Android.mk
@@ -58,6 +58,7 @@ test_c_flags = \
 
 test_src_files = \
     dirent_test.cpp \
+    eventfd_test.cpp \
     fenv_test.cpp \
     getauxval_test.cpp \
     getcwd_test.cpp \
diff --git a/tests/eventfd_test.cpp b/tests/eventfd_test.cpp
new file mode 100644
index 000000000..2c2c5f07e
--- /dev/null
+++ b/tests/eventfd_test.cpp
@@ -0,0 +1,47 @@
+/*
+ * Copyright (C) 2013 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 <gtest/gtest.h>
+
+#if !defined(__GLIBC__) // Android's prebuilt gcc's header files don't include <sys/eventfd.h>.
+
+#include <sys/eventfd.h>
+
+TEST(eventfd, smoke) {
+  unsigned int initial_value = 2;
+  int fd = eventfd(initial_value, O_NONBLOCK);
+  ASSERT_NE(fd, -1);
+
+  eventfd_t value = 123;
+  ASSERT_EQ(0, eventfd_read(fd, &value));
+  ASSERT_EQ(initial_value, value);
+
+  // Reading clears the counter.
+  ASSERT_EQ(-1, eventfd_read(fd, &value));
+  ASSERT_EQ(EAGAIN, errno);
+
+  // Values written are added until the next read.
+  ASSERT_EQ(0, eventfd_write(fd, 1));
+  ASSERT_EQ(0, eventfd_write(fd, 1));
+  ASSERT_EQ(0, eventfd_write(fd, 1));
+
+  ASSERT_EQ(0, eventfd_read(fd, &value));
+  ASSERT_EQ(3U, value);
+
+  close(fd);
+}
+
+#endif