diff --git a/IPython/nbconvert/utils/lexers.py b/IPython/nbconvert/utils/lexers.py
index 79f7eb8..97371b6 100644
--- a/IPython/nbconvert/utils/lexers.py
+++ b/IPython/nbconvert/utils/lexers.py
@@ -57,7 +57,7 @@ ipython_tokens = [
                                        using(BashLexer), Text)),
   (r'(%)(\w+)(.*\n)', bygroups(Operator, Keyword, Text)),
   (r'^(!!)(.+)(\n)', bygroups(Operator, using(BashLexer), Text)),
-  (r'(!)(.+)(\n)', bygroups(Operator, using(BashLexer), Text)),
+  (r'((?!=)!)(.+)(\n)', bygroups(Operator, using(BashLexer), Text)),
 ]
 
 def build_ipy_lexer(python3):