diff --git a/doc/src/sgml/runtime.sgml b/doc/src/sgml/runtime.sgml
index 927f062abe..1b2012d34a 100644
--- a/doc/src/sgml/runtime.sgml
+++ b/doc/src/sgml/runtime.sgml
@@ -539,7 +539,7 @@ DETAIL:  Failed system call was shmget(key=5440001, size=4011376640, 03600).
      probably means your kernel's limit on the size of shared memory is
      smaller than the work area <productname>PostgreSQL</productname>
      is trying to create (4011376640 bytes in this example).
-     This is more likely to happen if you have set <literal>shared_memory_type</literal>
+     This is only likely to happen if you have set <literal>shared_memory_type</literal>
      to <literal>sysv</literal>.  In that case, you
      can try starting the server with a smaller-than-normal number of
      buffers (<xref linkend="guc-shared-buffers"/>), or
@@ -1009,8 +1009,8 @@ psql: could not connect to server: No such file or directory
 <prompt>$</prompt> <userinput>sysctl -w kernel.shmmax=17179869184</userinput>
 <prompt>$</prompt> <userinput>sysctl -w kernel.shmall=4194304</userinput>
 </screen>
-        These settings can be preserved between reboots in
-        the file <filename>/etc/sysctl.conf</filename>.
+        To make these settings persist over reboots, see
+        <filename>/etc/sysctl.conf</filename>.
        </para>
 
       </listitem>
@@ -1287,7 +1287,7 @@ default:\
    </indexterm>
 
    <para>
-    The default virtual memory behavior is not
+    The default virtual memory behavior on Linux is not
     optimal for <productname>PostgreSQL</productname>. Because of the
     way that the kernel implements memory overcommit, the kernel might
     terminate the <productname>PostgreSQL</productname> postmaster (the