diff -r 60a124678842 -r 61f65dd6eeb9 lib/iec_std_lib.h
--- a/lib/iec_std_lib.h	Sun Jan 04 17:21:33 2009 +0100
+++ b/lib/iec_std_lib.h	Sun Jan 04 17:23:06 2009 +0100
@@ -559,7 +559,7 @@
                 shift += 1;
             }else if( c >= '.' ){ /* reset value */
                 res = 0;
-                fac = 1;
+                fac = IN->body[0] == '-' ? -1 : 1;
                 shift = 0;
             }            
         }