diff --git a/ctufit-thesis.cls b/ctufit-thesis.cls
index f941a5301ee7318b142163edb19718b926171eb5..fecc06b2d266e86070b6bbeb6e3ea83f58032221 100644
--- a/ctufit-thesis.cls
+++ b/ctufit-thesis.cls
@@ -322,7 +322,7 @@
   \noindent\ignorespaces}
 
 \newenvironment{abstract}{%
-  \vskip\bigskipamount
+  \vspace*{18mm}
   \noindent
   {{\frontchapterfont\begin{flushleft}{\color{heading}Abstract}\end{flushleft}}}%
   \bigskip