diff --git a/lib/dns/rcode.c b/lib/dns/rcode.c
index 2ea6d1c886..fefc2c1c3d 100644
--- a/lib/dns/rcode.c
+++ b/lib/dns/rcode.c
@@ -15,7 +15,7 @@
  * PERFORMANCE OF THIS SOFTWARE.
  */
 
-/* $Id: rcode.c,v 1.12 2009/10/22 02:21:30 each Exp $ */
+/* $Id: rcode.c,v 1.13 2010/11/16 00:53:36 marka Exp $ */
 
 #include <config.h>
 #include <ctype.h>
@@ -493,6 +493,9 @@ dns_rdataclass_format(dns_rdataclass_t rdclass,
 	isc_result_t result;
 	isc_buffer_t buf;
 
+	if (size == 0U)
+		return;
+
 	isc_buffer_init(&buf, array, size);
 	result = dns_rdataclass_totext(rdclass, &buf);
 	/*
@@ -504,8 +507,6 @@ dns_rdataclass_format(dns_rdataclass_t rdclass,
 		else
 			result = ISC_R_NOSPACE;
 	}
-	if (result != ISC_R_SUCCESS) {
-		snprintf(array, size, "<unknown>");
-		array[size - 1] = '\0';
-	}
+	if (result != ISC_R_SUCCESS)
+		strlcpy(array, "<unknown>", size);
 }
diff --git a/lib/dns/rdata.c b/lib/dns/rdata.c
index 77c7f7bd24..0c76ad7237 100644
--- a/lib/dns/rdata.c
+++ b/lib/dns/rdata.c
@@ -15,7 +15,7 @@
  * PERFORMANCE OF THIS SOFTWARE.
  */
 
-/* $Id: rdata.c,v 1.204 2009/12/04 21:09:33 marka Exp $ */
+/* $Id: rdata.c,v 1.205 2010/11/16 00:53:36 marka Exp $ */
 
 /*! \file */
 
@@ -963,6 +963,9 @@ dns_rdatatype_format(dns_rdatatype_t rdtype,
 	isc_result_t result;
 	isc_buffer_t buf;
 
+	if (size == 0U)
+		return;
+
 	isc_buffer_init(&buf, array, size);
 	result = dns_rdatatype_totext(rdtype, &buf);
 	/*
@@ -974,10 +977,8 @@ dns_rdatatype_format(dns_rdatatype_t rdtype,
 		else
 			result = ISC_R_NOSPACE;
 	}
-	if (result != ISC_R_SUCCESS) {
-		snprintf(array, size, "<unknown>");
-		array[size - 1] = '\0';
-	}
+	if (result != ISC_R_SUCCESS)
+		strlcpy(array, "<unknown>", size);
 }
 
 /*