diff --git a/book/book.tex b/book/book.tex
index 9e0368e..f7a26d8 100644
--- a/book/book.tex
+++ b/book/book.tex
@@ -2746,7 +2746,7 @@ \section{Exercises}
 \item Define a new function called 
 \verb"do_four" that takes a function object and a value
 and calls the function four times, passing the value
-as a parameter.  There should be only
+as an argument.  There should be only
 two statements in the body of this function, not four.
 
 \end{enumerate}
@@ -3353,7 +3353,7 @@ \section{Debugging}
 \index{interface}
 
 An interface is like a contract between a function and a caller.
-The caller agrees to provide certain parameters and the function
+The caller agrees to provide certain arguments and the function
 agrees to do certain work.
 
 For example, {\tt polyline} requires four arguments: {\tt t} has to be