Fix displayLevel overflow
diff --git a/lib/dictBuilder/cover.c b/lib/dictBuilder/cover.c
index 117acbf..6149784 100644
--- a/lib/dictBuilder/cover.c
+++ b/lib/dictBuilder/cover.c
@@ -969,7 +969,7 @@
   /* Initialization */
   COVER_best_init(&best);
   /* Turn down global display level to clean up display at level 2 and below */
-  g_displayLevel = parameters->zParams.notificationLevel - 1;
+  g_displayLevel = displayLevel == 0 ? 0 : displayLevel - 1;
   /* Loop through d first because each new value needs a new context */
   LOCALDISPLAYLEVEL(displayLevel, 2, "Trying %u different sets of parameters\n",
                     kIterations);