diff --git a/libraries/wutdevoptab/MutexWrapper.h b/libraries/wutdevoptab/MutexWrapper.h
index 1758a150..f2f63733 100644
--- a/libraries/wutdevoptab/MutexWrapper.h
+++ b/libraries/wutdevoptab/MutexWrapper.h
@@ -8,21 +8,14 @@ class MutexWrapper {
     MutexWrapper() = default;
 
     void init(const char *name) {
-       if (name) {
-          OSReport("Init mutex %s\n", name);
-       } else {
-          OSReport("Init mutex null");
-       }
        OSInitMutexEx(&mutex, name);
     }
 
     void lock() {
-       OSReport("lock mutex   %08X %08X %s\n", &mutex, mutex.tag, mutex.name);
        OSLockMutex(&mutex);
     }
 
     void unlock() {
-       OSReport("unlock mutex %08X %08X %s\n", &mutex, mutex.tag, mutex.name);
        OSUnlockMutex(&mutex);
        OSMemoryBarrier();
     }
diff --git a/libraries/wutdevoptab/devoptab_fsa_open.cpp b/libraries/wutdevoptab/devoptab_fsa_open.cpp
index 06eb82df..c20f17bd 100644
--- a/libraries/wutdevoptab/devoptab_fsa_open.cpp
+++ b/libraries/wutdevoptab/devoptab_fsa_open.cpp
@@ -23,6 +23,7 @@ int __wut_fsa_open(struct _reent *r,
    }
 
    bool createFileManually = false;
+   bool checkFileExists = false;
    // Map flags to open modes
    int commonFlagMask = O_CREAT | O_TRUNC | O_APPEND;
    if (((flags & O_ACCMODE) == O_RDONLY) && !(flags & commonFlagMask)) {
@@ -43,6 +44,14 @@ int __wut_fsa_open(struct _reent *r,
       // It's not possible to open a file with write only mode which doesn't truncate the file
       // Technically we could read from the file, but our read implementation is blocking this.
       fsMode = "r+";
+   } else if (((flags & O_ACCMODE) == O_WRONLY) && ((flags & commonFlagMask) == (O_APPEND))) {
+      // Cafe OS doesn't have a matching mode for this, so we have to check if the file exists.
+      checkFileExists = true;
+      fsMode = "a";
+   } else if (((flags & O_ACCMODE) == O_WRONLY) && ((flags & commonFlagMask) == (O_TRUNC))) {
+      // Cafe OS doesn't have a matching mode for this, so we have to check if the file exists.
+      checkFileExists = true;
+      fsMode = "w";
    } else {
       r->_errno = EINVAL;
       return -1;
@@ -69,16 +78,25 @@ int __wut_fsa_open(struct _reent *r,
    deviceData = (__wut_fsa_device_t *) r->deviceData;
 
    // Check if we need to create the file manually
-   if (createFileManually) {
+   if (checkFileExists || createFileManually || (flags & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT)) {
       FSStat stat;
       status = FSAGetStat(deviceData->clientHandle, file->name, &stat);
       if (status == FS_ERROR_NOT_FOUND) {
-         status = FSAOpenFileEx(deviceData->clientHandle, file->name, "w", translatedMode, openFlags, preAllocSize, &fd);
-         if (status == FS_ERROR_OK) {
-            FSACloseFile(deviceData->clientHandle, fd);
+         if (createFileManually) {
+            status = FSAOpenFileEx(deviceData->clientHandle, file->name, "w", translatedMode, openFlags, preAllocSize, &fd);
+            if (status == FS_ERROR_OK) {
+               FSACloseFile(deviceData->clientHandle, fd);
+               fd = -1;
+            }
+         } else if(checkFileExists) {
             fd = -1;
          }
       }
+      // If O_CREAT and O_EXCL are set, open() shall fail if the file exists.
+      if (status == FS_ERROR_OK && (flags & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT)) {
+         r->_errno = EEXIST;
+         return -1;
+      }
       if (status < 0) {
          r->_errno = __wut_fsa_translate_error(status);
          return -1;
@@ -94,12 +112,6 @@ int __wut_fsa_open(struct _reent *r,
       return -1;
    }
 
-   // If O_CREAT and O_EXCL are set, open() shall fail if the file exists.
-   if (flags & (O_EXCL | O_CREAT)) {
-      FSACloseFile(deviceData->clientHandle, fd);
-      r->_errno = EEXIST;
-      return -1;
-   }
 
    file->fd = fd;
    file->flags = (flags & (O_ACCMODE | O_APPEND | O_SYNC));
diff --git a/libraries/wutdevoptab/devoptab_fsa_rmdir.cpp b/libraries/wutdevoptab/devoptab_fsa_rmdir.cpp
index 1f6d951c..192bd6c5 100644
--- a/libraries/wutdevoptab/devoptab_fsa_rmdir.cpp
+++ b/libraries/wutdevoptab/devoptab_fsa_rmdir.cpp
@@ -16,11 +16,13 @@ int __wut_fsa_rmdir(struct _reent *r,
       return -1;
    }
 
+   deviceData = (__wut_fsa_device_t*) r->deviceData;
+
    status = FSARemove(deviceData->clientHandle, fixedPath);
    if (status < 0) {
       OSReport("FSARemove(0x%08X, %s) failed: %s\n", deviceData->clientHandle, fixedPath, FSAGetStatusStr(status));
       free(fixedPath);
-      r->_errno = status == FS_STATUS_EXISTS ? ENOTEMPTY : __wut_fsa_translate_error(status);
+      r->_errno = status == FS_ERROR_ALREADY_EXISTS ? ENOTEMPTY : __wut_fsa_translate_error(status);
       return -1;
    }