diff --git a/libion/ion.c b/libion/ion.c
index 4565efb..2db8845 100644
--- a/libion/ion.c
+++ b/libion/ion.c
@@ -34,7 +34,7 @@
 
 int ion_open()
 {
-    int fd = open("/dev/ion", O_RDWR);
+    int fd = open("/dev/ion", O_RDONLY);
     if (fd < 0)
         ALOGE("open /dev/ion failed!\n");
     return fd;
diff --git a/libion/tests/device_test.cpp b/libion/tests/device_test.cpp
index 0be52bf..eb3f7b6 100644
--- a/libion/tests/device_test.cpp
+++ b/libion/tests/device_test.cpp
@@ -46,7 +46,7 @@
 void Device::SetUp()
 {
     IonAllHeapsTest::SetUp();
-    m_deviceFd = open("/dev/ion-test", O_RDWR);
+    m_deviceFd = open("/dev/ion-test", O_RDONLY);
     ASSERT_GE(m_deviceFd, 0);
 }