diff --git a/files/mvregex b/files/mvregex
index 93d611f..a5f010d 100755
--- a/files/mvregex
+++ b/files/mvregex
@@ -10,7 +10,7 @@ function helpexit() {
     echo '    -n to match non-ascii and non-printable characters, and replace to [arg1]'
     echo '    -f to replace match [arg1] with format [arg2], ex: -f "[0-9]\+" "%04d"'
     echo '    -p to replace problematic characters [^\w()[]-.] with [arg1]'
-    echo '    -a to replace non-alphanumeric(+dot) characters [^\w.] with [arg1]'
+    echo '    -a to replace non-alphanumeric(+dot) characters [^\w_-.] with [arg1]'
     echo '    -u Unidecode to nearest ascii representation'
     
     exit
@@ -51,7 +51,7 @@ do  [[ "${!i}" = "-h" ]] && helpexit
             continue
         }
     [[ "${!i}" = "-a" ]] && {
-            SRC='[^0-9a-zA-Z.]'
+            SRC='[^0-9a-zA-Z.-_]'
             continue
         }
     [[ -z "$SRC" ]] && {