diff --git a/src/command_line.py b/src/command_line.py
index 549b8ae..00c27fa 100644
--- a/src/command_line.py
+++ b/src/command_line.py
@@ -47,6 +47,7 @@ options['l'] = [ 'align'        , 'Align arrays using compiler directives. Sets
 options['s'] = [ 'substitute'   , 'Substitute values for loop max values', 1 ]
 options['r'] = [ 'no_directives', 'Ignore compiler directives !DEC$ and !DIR$', 0 ]
 options['n'] = [ 'inline'       , 'all|providers|builders : Force inlining of providers or builders', 1 ]
+options['u'] = [ 'unused'       , 'Print unused providers', 0 ]
 
 class CommandLine(object):
 
diff --git a/src/variable.py b/src/variable.py
index e07f2d5..f9eb512 100644
--- a/src/variable.py
+++ b/src/variable.py
@@ -618,6 +618,8 @@ class Variable(object):
         from variables import variables
         if '_needed_by' not in self.__dict__:
           import parsed_text
+        if command_line.do_unused and self.needed_by == []:
+          error.warn(None, "Provider %s is not used"%self.name)
         result = []
         for x in self.needed_by:
           result.append(x)