diff --git a/Utils.cpp b/Utils.cpp
index 04c3956..ce1f777 100644
--- a/Utils.cpp
+++ b/Utils.cpp
@@ -766,7 +766,7 @@ bool IsRunningInEmulator() {
 }
 
 status_t UnmountTree(const std::string& prefix) {
-    FILE* fp = setmntent("/proc/mounts", "r");
+    FILE* fp = setmntent("/proc/mounts", "re");
     if (fp == NULL) {
         PLOG(ERROR) << "Failed to open /proc/mounts";
         return -errno;
diff --git a/VolumeManager.cpp b/VolumeManager.cpp
index 21136cf..59a3d1b 100644
--- a/VolumeManager.cpp
+++ b/VolumeManager.cpp
@@ -589,7 +589,7 @@ int VolumeManager::unmountAll() {
 
     // Worst case we might have some stale mounts lurking around, so
     // force unmount those just to be safe.
-    FILE* fp = setmntent("/proc/mounts", "r");
+    FILE* fp = setmntent("/proc/mounts", "re");
     if (fp == NULL) {
         PLOG(ERROR) << "Failed to open /proc/mounts";
         return -errno;