diff --git a/hdathesis.sty b/hdathesis.sty
index 3bd70d8..f839168 100644
--- a/hdathesis.sty
+++ b/hdathesis.sty
@@ -57,7 +57,7 @@
 \theoremstyle{plain} {{\theorembodyfont{\normalfont}
 \newtheorem{Definition}{Definition}}
 \newcommand{\qed}{\hfill \mbox{\raggedright \rule{.07in}{.1in}}}
-\newenvironment{proof}{\vspace{1ex}\noindent{\bf Proof}\hspace{0.5em}}
+\newenvironment{proof}{\vspace{1ex}\noindent{\textbf Proof}\hspace{0.5em}}
 	{\hfill\qed\vspace{2ex}}
 
 %*******************************************************************************