diff --git a/src/ui.c b/src/ui.c
index 2fc2cea..d8c8067 100644
--- a/src/ui.c
+++ b/src/ui.c
@@ -2165,15 +2165,15 @@ _evisum_key_down_cb(void *data, Evas *e, Evas_Object *obj, void *event_info)
    if (!ev || !ev->keyname)
      return;
 
-   if (!strcasecmp(ev->keyname, "K"))
+    if ((ev->keyname[0] == 'K' || ev->keyname[0] == 'k') && !ev->keyname[1])
      {
         ui->data_unit = DATA_UNIT_KB;
      }
-   else if (!strcasecmp(ev->keyname, "M"))
+   else if ((ev->keyname[0] == 'M' || ev->keyname[0] == 'm') && !ev->keyname[1])
      {
         ui->data_unit = DATA_UNIT_MB;
      }
-   else if (!strcasecmp(ev->keyname, "G"))
+   else if ((ev->keyname[0] == 'G' || ev->keyname[0] == 'g') && !ev->keyname[1])
      {
         ui->data_unit = DATA_UNIT_GB;
      }