diff --git a/src/ptserver/ptprocs.c b/src/ptserver/ptprocs.c
index f9f48fc689..181cc2860f 100644
--- a/src/ptserver/ptprocs.c
+++ b/src/ptserver/ptprocs.c
@@ -687,7 +687,7 @@ idToName(struct rx_call *call, idlist *aid, namelist *aname)
 	return 0;
     if (size < 0 || size > INT_MAX / PR_MAXNAMELEN)
 	return PRTOOMANY;
-    aname->namelist_val = (prname *) malloc(size * PR_MAXNAMELEN);
+    aname->namelist_val = (prname *) calloc(size, PR_MAXNAMELEN);
     aname->namelist_len = 0;
     if (aname->namelist_val == 0)
 	return PRNOMEM;