diff --git a/src/ecopcr.c b/src/ecopcr.c
index 0c9d285..f203dd6 100644
--- a/src/ecopcr.c
+++ b/src/ecopcr.c
@@ -72,6 +72,8 @@ static void PrintHelp()
         PP      "column 18 : amplification length\n");
         PP      "column 19 : sequence description\n");
         PP      "------------------------------------------\n");
+        PP		" https://www.grenoble.prabi.fr/trac/ecoPCR/wiki");
+        PP      "------------------------------------------\n\n");        
         PP      "\n");
 
 }
@@ -383,7 +385,15 @@ int main(int argc, char **argv)
 	}
 	else
 		errflag++;
-                       
+	
+	if (prefix == NULL)
+	{
+		prefix = getenv("ECOPCRDB");
+		if (prefix == NULL)
+			errflag++;
+	}
+	
+	                  
     if (!oligo1 || !oligo2)
     		errflag++;