diff --git a/fs_local.go b/fs_local.go
index 201ae93..7668612 100644
--- a/fs_local.go
+++ b/fs_local.go
@@ -63,6 +63,18 @@ func fileInfoFromOS(p string, fi os.FileInfo) *FileInfo {
 	}
 }
 
+func errFromOS(err error) error {
+	if os.IsNotExist(err) {
+		return NewHTTPError(http.StatusNotFound, err)
+	} else if os.IsPermission(err) {
+		return NewHTTPError(http.StatusForbidden, err)
+	} else if os.IsTimeout(err) {
+		return NewHTTPError(http.StatusServiceUnavailable, err)
+	} else {
+		return err
+	}
+}
+
 func (fs LocalFileSystem) Stat(ctx context.Context, name string) (*FileInfo, error) {
 	p, err := fs.localPath(name)
 	if err != nil {
@@ -70,7 +82,7 @@ func (fs LocalFileSystem) Stat(ctx context.Context, name string) (*FileInfo, err
 	}
 	fi, err := os.Stat(p)
 	if err != nil {
-		return nil, err
+		return nil, errFromOS(err)
 	}
 	return fileInfoFromOS(name, fi), nil
 }
@@ -99,7 +111,7 @@ func (fs LocalFileSystem) ReadDir(ctx context.Context, name string, recursive bo
 		}
 		return nil
 	})
-	return l, err
+	return l, errFromOS(err)
 }
 
 func (fs LocalFileSystem) Create(ctx context.Context, name string) (io.WriteCloser, error) {
@@ -107,7 +119,8 @@ func (fs LocalFileSystem) Create(ctx context.Context, name string) (io.WriteClos
 	if err != nil {
 		return nil, err
 	}
-	return os.Create(p)
+	wc, err := os.Create(p)
+	return wc, errFromOS(err)
 }
 
 func (fs LocalFileSystem) RemoveAll(ctx context.Context, name string) error {
@@ -119,10 +132,10 @@ func (fs LocalFileSystem) RemoveAll(ctx context.Context, name string) error {
 	// WebDAV semantics are that it should return a "404 Not Found" error in
 	// case the resource doesn't exist. We need to Stat before RemoveAll.
 	if _, err = os.Stat(p); err != nil {
-		return err
+		return errFromOS(err)
 	}
 
-	return os.RemoveAll(p)
+	return errFromOS(os.RemoveAll(p))
 }
 
 func (fs LocalFileSystem) Mkdir(ctx context.Context, name string) error {
@@ -130,20 +143,21 @@ func (fs LocalFileSystem) Mkdir(ctx context.Context, name string) error {
 	if err != nil {
 		return err
 	}
-	return os.Mkdir(p, 0755)
+	return errFromOS(os.Mkdir(p, 0755))
 }
 
 func copyRegularFile(src, dst string, perm os.FileMode) error {
 	srcFile, err := os.Open(src)
 	if err != nil {
-		return err
+		return errFromOS(err)
 	}
 	defer srcFile.Close()
 
 	dstFile, err := os.OpenFile(dst, os.O_RDWR|os.O_CREATE|os.O_TRUNC, perm)
-	if err != nil {
-		// TODO: send http.StatusConflict on os.IsNotExist
-		return err
+	if os.IsNotExist(err) {
+		return NewHTTPError(http.StatusConflict, err)
+	} else if err != nil {
+		return errFromOS(err)
 	}
 	defer dstFile.Close()
 
@@ -169,21 +183,21 @@ func (fs LocalFileSystem) Copy(ctx context.Context, src, dst string, options *Co
 
 	srcInfo, err := os.Stat(srcPath)
 	if err != nil {
-		return false, err
+		return false, errFromOS(err)
 	}
 	srcPerm := srcInfo.Mode() & os.ModePerm
 
 	if _, err := os.Stat(dstPath); err != nil {
 		if !os.IsNotExist(err) {
-			return false, err
+			return false, errFromOS(err)
 		}
 		created = true
 	} else {
 		if options.NoOverwrite {
-			return false, os.ErrExist
+			return false, NewHTTPError(http.StatusPreconditionFailed, os.ErrExist)
 		}
 		if err := os.RemoveAll(dstPath); err != nil {
-			return false, err
+			return false, errFromOS(err)
 		}
 	}
 
@@ -194,7 +208,7 @@ func (fs LocalFileSystem) Copy(ctx context.Context, src, dst string, options *Co
 
 		if fi.IsDir() {
 			if err := os.Mkdir(dstPath, srcPerm); err != nil {
-				return err
+				return errFromOS(err)
 			}
 		} else {
 			if err := copyRegularFile(srcPath, dstPath, srcPerm); err != nil {
@@ -208,7 +222,7 @@ func (fs LocalFileSystem) Copy(ctx context.Context, src, dst string, options *Co
 		return nil
 	})
 	if err != nil {
-		return false, err
+		return false, errFromOS(err)
 	}
 
 	return created, nil
@@ -226,20 +240,20 @@ func (fs LocalFileSystem) Move(ctx context.Context, src, dst string, options *Mo
 
 	if _, err := os.Stat(dstPath); err != nil {
 		if !os.IsNotExist(err) {
-			return false, err
+			return false, errFromOS(err)
 		}
 		created = true
 	} else {
 		if options.NoOverwrite {
-			return false, os.ErrExist
+			return false, NewHTTPError(http.StatusPreconditionFailed, os.ErrExist)
 		}
 		if err := os.RemoveAll(dstPath); err != nil {
-			return false, err
+			return false, errFromOS(err)
 		}
 	}
 
 	if err := os.Rename(srcPath, dstPath); err != nil {
-		return false, err
+		return false, errFromOS(err)
 	}
 
 	return created, nil
diff --git a/server.go b/server.go
index 984c763..bf3ec10 100644
--- a/server.go
+++ b/server.go
@@ -57,7 +57,7 @@ type backend struct {
 
 func (b *backend) Options(r *http.Request) (caps []string, allow []string, err error) {
 	fi, err := b.FileSystem.Stat(r.Context(), r.URL.Path)
-	if os.IsNotExist(err) {
+	if internal.IsNotFound(err) {
 		return nil, []string{http.MethodOptions, http.MethodPut, "MKCOL"}, nil
 	} else if err != nil {
 		return nil, nil, err
@@ -80,9 +80,7 @@ func (b *backend) Options(r *http.Request) (caps []string, allow []string, err e
 
 func (b *backend) HeadGet(w http.ResponseWriter, r *http.Request) error {
 	fi, err := b.FileSystem.Stat(r.Context(), r.URL.Path)
-	if os.IsNotExist(err) {
-		return &internal.HTTPError{Code: http.StatusNotFound, Err: err}
-	} else if err != nil {
+	if err != nil {
 		return err
 	}
 	if fi.IsDir {
@@ -121,9 +119,7 @@ func (b *backend) PropFind(r *http.Request, propfind *internal.PropFind, depth i
 	// TODO: use partial error Response on error
 
 	fi, err := b.FileSystem.Stat(r.Context(), r.URL.Path)
-	if os.IsNotExist(err) {
-		return nil, &internal.HTTPError{Code: http.StatusNotFound, Err: err}
-	} else if err != nil {
+	if err != nil {
 		return nil, err
 	}
 
@@ -212,11 +208,7 @@ func (b *backend) Put(r *http.Request) (*internal.Href, error) {
 }
 
 func (b *backend) Delete(r *http.Request) error {
-	err := b.FileSystem.RemoveAll(r.Context(), r.URL.Path)
-	if os.IsNotExist(err) {
-		return &internal.HTTPError{Code: http.StatusNotFound, Err: err}
-	}
-	return err
+	return b.FileSystem.RemoveAll(r.Context(), r.URL.Path)
 }
 
 func (b *backend) Mkcol(r *http.Request) error {
@@ -224,7 +216,7 @@ func (b *backend) Mkcol(r *http.Request) error {
 		return internal.HTTPErrorf(http.StatusUnsupportedMediaType, "webdav: request body not supported in MKCOL request")
 	}
 	err := b.FileSystem.Mkdir(r.Context(), r.URL.Path)
-	if os.IsNotExist(err) {
+	if internal.IsNotFound(err) {
 		return &internal.HTTPError{Code: http.StatusConflict, Err: err}
 	}
 	return err