Index: /trunk/FACT++/src/Readline.cc
===================================================================
--- /trunk/FACT++/src/Readline.cc	(revision 15074)
+++ /trunk/FACT++/src/Readline.cc	(revision 15075)
@@ -1311,6 +1311,6 @@
 
     const string str(buf);
-    if (Tools::Trim(str)!=".q")
-        if (history_search_pos(str.c_str(), -1, history_length-1)!=history_length-1)
+    if (Tools::Trim(str)!=".q" && !Tools::Trim(str).empty())
+        if (history_length==0 || history_search_pos(str.c_str(), -1, history_length-1)!=history_length-1)
             add_history(buf);