diff --git a/mininet/cli.py b/mininet/cli.py
index 2ff982515e3a4bad863dc56bb1e524ddf1157f9b..3df99ada1bf96d73e354da9b29d8b4f50bffd92a 100644
--- a/mininet/cli.py
+++ b/mininet/cli.py
@@ -297,6 +297,7 @@ def do_source( self, line ):
                     break
         except IOError:
             error( 'error reading file %s\n' % args[ 0 ] )
+        self.inputFile.close()
         self.inputFile = None
 
     def do_dpctl( self, line ):