diff --git a/doc/if.html b/doc/if.html
index 978d35c13b..a29aa0d10d 100644
--- a/doc/if.html
+++ b/doc/if.html
@@ -115,7 +115,7 @@ syntax.  Note that each expression is a single argument within the if
 command.  Thus if you want to include spaces in the expression for
 clarity, you must enclose the entire expression in quotes.
 </P>
-<P>An expression is built out of numbers
+<P>An expression is built out of numbers:
 </P>
 <PRE>0.2, 100, 1.0e20, -15.4, etc 
 </PRE>
@@ -127,7 +127,7 @@ clarity, you must enclose the entire expression in quotes.
 or another Boolean expression.
 </P>
 <P>If a variable is used it must produce a number when evaluated and
-substituted for in the expression.
+substituted for in the expression, else an error will be generated.
 </P>
 <P>Expressions are evaluated left to right and have the usual C-style
 precedence: the 4 relational operators "<", "<=", ">", and ">=" have
diff --git a/doc/if.txt b/doc/if.txt
index 4ccde3453d..b006a5ebff 100644
--- a/doc/if.txt
+++ b/doc/if.txt
@@ -111,7 +111,7 @@ syntax.  Note that each expression is a single argument within the if
 command.  Thus if you want to include spaces in the expression for
 clarity, you must enclose the entire expression in quotes.
 
-An expression is built out of numbers
+An expression is built out of numbers:
 
 0.2, 100, 1.0e20, -15.4, etc :pre
 
@@ -123,7 +123,7 @@ Each A and B is a number or a variable reference like $a or $\{abc\},
 or another Boolean expression.
 
 If a variable is used it must produce a number when evaluated and
-substituted for in the expression.
+substituted for in the expression, else an error will be generated.
 
 Expressions are evaluated left to right and have the usual C-style
 precedence: the 4 relational operators "<", "<=", ">", and ">=" have