diff --git a/input/chapter04/chapter04.xml b/input/chapter04/chapter04.xml
index c8d309d..aefb7aa 100644
--- a/input/chapter04/chapter04.xml
+++ b/input/chapter04/chapter04.xml
@@ -812,7 +812,7 @@ run next.  All possible tasks are kept on a
 <emphasis>run queue</emphasis>, which is simply a linked list of
 processes which the kernel knows are in a "runnable" state (i.e. not
 waiting on disk activity or otherwise asleep).  The problem arises
-that to calculate the next process to run, every possible runnable
+when to calculate the next process to run, every possible runnable
 process must have its goodness calculated and the one with the highest
 goodness ``wins''.  You can see that for more tasks, it will take
 longer and longer to decide which processes will run next.</para>
diff --git a/input/chapter06/chapter06.xml b/input/chapter06/chapter06.xml
index 45c3728..cc8f054 100644
--- a/input/chapter06/chapter06.xml
+++ b/input/chapter06/chapter06.xml
@@ -103,7 +103,7 @@
       <para>The first step of compiling a source file to an executable
     file is converting the code from the high level, human
     understandable language to <emphasis>assembly code</emphasis>.  We
-    know from previous chapters than assembly code works directly with
+    know from previous chapters that assembly code works directly with
     the instructions and registers provided by the processor.</para>
       <para>The compiler is the most complex step of process for a
     number of reasons.  Firstly, humans are very unpredictable and