diff --git a/slic3r.pl b/slic3r.pl
index 148092245..c3e02a2f4 100755
--- a/slic3r.pl
+++ b/slic3r.pl
@@ -219,7 +219,10 @@ Usage: slic3r.pl [ OPTIONS ] [ file.stl ] [ file2.stl ] ...
                         more than once to load options from multiple files.
     -o, --output <file> File to output gcode to (by default, the file will be saved
                         into the same directory as the input file using the 
-                        --output-filename-format to generate the filename)
+                        --output-filename-format to generate the filename.) If a
+                        directory is specified for this option, the output will
+                        be saved under that directory, and the filename will be
+                        generated by --output-filename-format.
   
   Non-slicing actions (no G-code will be generated):
     --repair            Repair given STL files and save them as <name>_fixed.obj