diff --git a/openflexure_microscope/exceptions.py b/openflexure_microscope/exceptions.py
index 73db926f..ee526ae4 100644
--- a/openflexure_microscope/exceptions.py
+++ b/openflexure_microscope/exceptions.py
@@ -15,6 +15,11 @@ class LockError(ThreadError):
             self.message = LockError.ERROR_CODES[code]
         else:
             self.message = "Unknown error."
-        print("{}: {}".format(self.code, self.message))
+        
+        self.string = "{}: {}".format(self.code, self.message)
+        print(self.string)
 
-        ThreadError.__init__(self)
\ No newline at end of file
+        ThreadError.__init__(self)
+    
+    def __str__(self):
+        return self.string
\ No newline at end of file