diff --git a/doc/guide/bind10-guide.xml b/doc/guide/bind10-guide.xml
index 4184b16d9b..b35b4068d2 100644
--- a/doc/guide/bind10-guide.xml
+++ b/doc/guide/bind10-guide.xml
@@ -3504,7 +3504,7 @@ const std::string HARDCODED_SERVER_ID = "192.0.2.1";</screen>
       <itemizedlist>
           <listitem>
             <simpara>RFC2131: Supported messages are DISCOVER, OFFER,
-            REQUEST, ACK, NACK, RELEASE.</simpara>
+            REQUEST, ACK, NAK, RELEASE.</simpara>
           </listitem>
           <listitem>
             <simpara>RFC2132: Supported options are: PAD (0),
diff --git a/src/bin/dhcp4/dhcp4_messages.mes b/src/bin/dhcp4/dhcp4_messages.mes
index 0ee5139a7a..f15d00e193 100644
--- a/src/bin/dhcp4/dhcp4_messages.mes
+++ b/src/bin/dhcp4/dhcp4_messages.mes
@@ -123,10 +123,11 @@ This debug message indicates that an address was released properly. It
 is a normal operation during client shutdown.
 
 % DHCP4_RELEASE_EXCEPTION exception %1 while trying to release address %2
-This error message indicates that an exception was raised during an attempt
-to process RELEASE message. This does not affect the client as it does not expect
-any response for RELEASE message. Depending on the nature of exception it may
-affect future server operation.
+This message is output when an error was encountered during an attempt
+to process a RELEASE message. The error will not affect the client,
+which does not expect any response from the server for RELEASE
+messages. Depending on the nature of problem, it may affect future
+server operation.
 
 % DHCP4_RELEASE_FAIL failed to remove lease for address %1 for duid %2, hwaddr %3
 This error message indicates that the software failed to remove a