diff --git a/src/CryFuse.cpp b/src/CryFuse.cpp
index 65447269..7188fa16 100644
--- a/src/CryFuse.cpp
+++ b/src/CryFuse.cpp
@@ -206,8 +206,9 @@ int CryFuse::read(const path &path, char *buf, size_t size, off_t offset, fuse_f
   //printf("read(%s, _, %zu, %zu, _)\n", path.c_str(), size, offset);
   UNUSED(path);
   try {
-    _device->read(fileinfo->fh, buf, size, offset);
-    return 0;
+    //printf("Reading from file %d\n", fileinfo->fh);
+    //fflush(stdout);
+    return _device->read(fileinfo->fh, buf, size, offset);
   } catch (CryErrnoException &e) {
     return -e.getErrno();
   }
@@ -218,7 +219,7 @@ int CryFuse::write(const path &path, const char *buf, size_t size, off_t offset,
   UNUSED(path);
   try {
     _device->write(fileinfo->fh, buf, size, offset);
-    return 0;
+    return size;
   } catch (CryErrnoException &e) {
     return -e.getErrno();
   }
diff --git a/src/cryfs_lib/CryDevice.cpp b/src/cryfs_lib/CryDevice.cpp
index 652d440a..dfdd7b03 100644
--- a/src/cryfs_lib/CryDevice.cpp
+++ b/src/cryfs_lib/CryDevice.cpp
@@ -74,8 +74,8 @@ void CryDevice::ftruncate(int descriptor, off_t size) {
   _open_files.get(descriptor)->truncate(size);
 }
 
-void CryDevice::read(int descriptor, void *buf, size_t count, off_t offset) {
-  _open_files.get(descriptor)->read(buf, count, offset);
+int CryDevice::read(int descriptor, void *buf, size_t count, off_t offset) {
+  return _open_files.get(descriptor)->read(buf, count, offset);
 }
 
 void CryDevice::write(int descriptor, const void *buf, size_t count, off_t offset) {
diff --git a/src/cryfs_lib/CryDevice.h b/src/cryfs_lib/CryDevice.h
index f5a97e9f..e667a078 100644
--- a/src/cryfs_lib/CryDevice.h
+++ b/src/cryfs_lib/CryDevice.h
@@ -28,7 +28,7 @@ public:
 	void fstat(int descriptor, struct ::stat *stbuf);
 	void truncate(const bf::path &path, off_t size);
 	void ftruncate(int descriptor, off_t size);
-	void read(int descriptor, void *buf, size_t count, off_t offset);
+	int read(int descriptor, void *buf, size_t count, off_t offset);
 	void write(int descriptor, const void *buf, size_t count, off_t offset);
 	void fsync(int descriptor);
 	void fdatasync(int descriptor);
diff --git a/src/cryfs_lib/CryOpenFile.cpp b/src/cryfs_lib/CryOpenFile.cpp
index 89b330a1..e85f4dc2 100644
--- a/src/cryfs_lib/CryOpenFile.cpp
+++ b/src/cryfs_lib/CryOpenFile.cpp
@@ -27,14 +27,21 @@ void CryOpenFile::truncate(off_t size) const {
   CHECK_RETVAL(retval);
 }
 
-void CryOpenFile::read(void *buf, size_t count, off_t offset) {
+int CryOpenFile::read(void *buf, size_t count, off_t offset) {
+  //printf("Reading from real descriptor %d (%d, %d)\n", _descriptor, offset, count);
+  //fflush(stdout);
   int retval = ::pread(_descriptor, buf, count, offset);
   CHECK_RETVAL(retval);
+  //printf("retval: %d, count: %d\n", retval, count);
+  //fflush(stdout);
+  assert(retval <= count);
+  return retval;
 }
 
 void CryOpenFile::write(const void *buf, size_t count, off_t offset) {
   int retval = ::pwrite(_descriptor, buf, count, offset);
   CHECK_RETVAL(retval);
+  assert(retval == count);
 }
 
 void CryOpenFile::fsync() {
diff --git a/src/cryfs_lib/CryOpenFile.h b/src/cryfs_lib/CryOpenFile.h
index 8bd45598..ca71123f 100644
--- a/src/cryfs_lib/CryOpenFile.h
+++ b/src/cryfs_lib/CryOpenFile.h
@@ -17,7 +17,7 @@ public:
 
   void stat(struct ::stat *result) const;
   void truncate(off_t size) const;
-  void read(void *buf, size_t count, off_t offset);
+  int read(void *buf, size_t count, off_t offset);
   void write(const void *buf, size_t count, off_t offset);
   void fsync();
   void fdatasync();