diff --git a/src/arachne.c b/src/arachne.c
index 2790c29..70d2b65 100644
--- a/src/arachne.c
+++ b/src/arachne.c
@@ -1883,7 +1883,7 @@ prune_bounds ()
       if (sys->output == PROOF)
 	{
 	  indentPrint ();
-	  eprintf ("Pruned: proof tree too deep: %i (--max-depth %i switch)\n",
+	  eprintf ("Pruned: proof tree too deep: %i (-d %i switch)\n",
 		   proofDepth, sys->switch_maxproofdepth);
 	}
       return 1;
diff --git a/src/main.c b/src/main.c
index 0d87678..8f84392 100644
--- a/src/main.c
+++ b/src/main.c
@@ -119,7 +119,7 @@ main (int argc, char **argv)
     arg_int0 ("l", "max-length", NULL,
 	      "prune traces longer than <int> events.");
   struct arg_int *switch_prune_proof_depth =
-    arg_int0 (NULL, "max-depth", NULL,
+    arg_int0 ("d", "max-depth", NULL,
 	      "prune proof deeper than <int> splits.");
   struct arg_lit *switch_incremental_trace_length =
     arg_lit0 (NULL, "increment-traces",