diff --git a/rtgui/main.cc b/rtgui/main.cc
index f345fecc8..8dc6b615c 100644
--- a/rtgui/main.cc
+++ b/rtgui/main.cc
@@ -131,7 +131,7 @@ int processLineParams ( int argc, char **argv )
         currParam = currParam.substr (1, currParam.length() - 2);
 #endif
 
-        if ( currParam.at (0) == '-' ) {
+        if ( currParam.at (0) == '-' && currParam.size() > 1 ) {
             switch ( currParam.at (1) ) {
 #ifdef WIN32