diff --git a/sphinx/ext/graphviz.py b/sphinx/ext/graphviz.py
index 59426bf88..3c2bacee3 100644
--- a/sphinx/ext/graphviz.py
+++ b/sphinx/ext/graphviz.py
@@ -139,7 +139,6 @@ class GraphvizSimple(Directive):
 
 def render_dot(self, code, options, format, prefix='graphviz'):
     """Render graphviz code into a PNG or PDF output file."""
-
     hashkey = (code + str(options) + \
               str(self.builder.config.graphviz_dot) + \
               str(self.builder.config.graphviz_dot_args)
diff --git a/sphinx/ext/inheritance_diagram.py b/sphinx/ext/inheritance_diagram.py
index 3927d78de..467e66293 100644
--- a/sphinx/ext/inheritance_diagram.py
+++ b/sphinx/ext/inheritance_diagram.py
@@ -52,7 +52,6 @@ from sphinx.ext.graphviz import render_dot_html, render_dot_latex, \
     render_dot_texinfo
 from sphinx.pycode import ModuleAnalyzer
 from sphinx.util.compat import Directive
-from sphinx.util import get_module_source
 
 
 class_sig_re = re.compile(r'''^([\w.]*\.)?    # module names