diff --git a/sphinx/texinputs/sphinx.sty b/sphinx/texinputs/sphinx.sty
index 3f11a098b..f3608c376 100644
--- a/sphinx/texinputs/sphinx.sty
+++ b/sphinx/texinputs/sphinx.sty
@@ -546,12 +546,12 @@
 \newlength{\py@argswidth}
 \newcommand{\py@sigparams}[2]{%
   \parbox[t]{\py@argswidth}{#1\sphinxcode{)}#2}}
-\newcommand{\pysigline}[1]{\item[#1]\nopagebreak}
+\newcommand{\pysigline}[1]{\item[{#1}]\nopagebreak}
 \newcommand{\pysiglinewithargsret}[3]{%
   \settowidth{\py@argswidth}{#1\sphinxcode{(}}%
   \addtolength{\py@argswidth}{-2\py@argswidth}%
   \addtolength{\py@argswidth}{\linewidth}%
-  \item[#1\sphinxcode{(}\py@sigparams{#2}{#3}]}
+  \item[{#1\sphinxcode{(}\py@sigparams{#2}{#3}}]}
 
 % Production lists
 %
@@ -774,7 +774,7 @@
 %
 \newenvironment{definitions}{%
   \begin{description}%
-  \def\term##1{\item[##1]\mbox{}\\*[0mm]}
+  \def\term##1{\item[{##1}]\mbox{}\\*[0mm]}
 }{%
   \end{description}%
 }