diff --git a/file.php b/file.php
index c9d7ec9..43e8c3f 100644
--- a/file.php
+++ b/file.php
@@ -274,6 +274,14 @@ class file
     $this->debug (2, "lockEX ($filename)");
     $filename = $this->realpath ($filename);
     $this->checkPathRW (dirname ($filename));
+    if (! file_exists ($filename))
+      throw new \Exception (sprintf (dgettext ("domframework",
+                            "File '%s' doesn't exists : could not be locked"),
+                            $filename), 500);
+    if (! is_readable ($filename))
+      throw new \Exception (sprintf (dgettext ("domframework",
+                            "File '%s' is not readable : could not be locked"),
+                            $filename), 500);
     $this->locks[$filename] = fopen ($filename, "rt");
     return flock ($this->locks[$filename], LOCK_EX);
   }
@@ -288,6 +296,14 @@ class file
     $this->debug (2, "lockSH ($filename)");
     $filename = $this->realpath ($filename);
     $this->checkPathRW (dirname ($filename));
+    if (! file_exists ($filename))
+      throw new \Exception (sprintf (dgettext ("domframework",
+                            "File '%s' doesn't exists : could not be locked"),
+                            $filename), 500);
+    if (! is_readable ($filename))
+      throw new \Exception (sprintf (dgettext ("domframework",
+                            "File '%s' is not readable : could not be locked"),
+                            $filename), 500);
     $this->locks[$filename] = fopen ($filename, "rt");
     return flock ($this->locks[$filename], LOCK_SH);
   }
@@ -311,7 +327,6 @@ class file
     return $res;
   }
 
-
   /** Calculate the md5 sum of a file
     * @param $filename The file to hash
     * @return the calulated hash
@@ -327,9 +342,9 @@ class file
                                        "File '%s' is not a file"),
                                        $filename), 500);
     if (! is_readable ($filename))
-      throw new \Exception (sprintf (dgettext ("domframework",
-                                       "File '%s' is not readable"),
-                                       $filename), 500);
+    throw new \Exception (sprintf (dgettext ("domframework",
+                                     "File '%s' is not readable"),
+                                     $filename), 500);
     return md5_file ($filename);
   }