diff --git a/Styles/softlab-thesis.cls b/Styles/softlab-thesis.cls
index 9ebc642d3cf91b69f180aac583be8bab0211bce3..87bc070d204cf8b2f00ed6cfed604273fd1bb567 100644
--- a/Styles/softlab-thesis.cls
+++ b/Styles/softlab-thesis.cls
@@ -1470,6 +1470,7 @@
     \@author, \\[6pt]
     \@locationgr, \@date@defense
   \end{flushright}
+  \ifx\@TRnumber\@empty\else
   \footacknowledgement{%
     Ξ— Ρργασία Ξ±Ο…Ο„Ξ� Ρίναι Ρπίσης διαθέσιμη ως ΀ΡχνικΞ� Αναφορά
     \@TRnumber, Ξ•ΞΈΞ½ΞΉΞΊΟŒ ΞœΞ΅Ο„ΟƒΟŒΞ²ΞΉΞΏ ΠολυτΡχνΡίο, ΣχολΞ� Ξ—Ξ»Ξ΅ΞΊΟ„ΟΞΏΞ»ΟŒΞ³Ο‰Ξ½
@@ -1482,6 +1483,7 @@
     FTP: & \texttt{ftp://ftp.softlab.ntua.gr/pub/techrep/}
     \end{tabular}
   }
+  \fi
   \newpage%
   \endgroup%
   \end{greek}%
@@ -1498,6 +1500,7 @@
     \@authoren, \\[6pt]
     \@locationen, \@date@defenseen
   \end{flushright}
+  \ifx\@TRnumber\@empty\else
   \footacknowledgement{%
     This thesis is also available as Technical Report \@TRnumber,
     National Technical University of Athens,
@@ -1510,6 +1513,7 @@
     FTP: & \texttt{ftp://ftp.softlab.ntua.gr/pub/techrep/}
     \end{tabular}
   }
+  \fi
   \newpage%
   \endgroup%
   \end{english}%