diff --git a/Doc/Manual/Preprocessor.html b/Doc/Manual/Preprocessor.html
index d7917c41a..8d41efccf 100644
--- a/Doc/Manual/Preprocessor.html
+++ b/Doc/Manual/Preprocessor.html
@@ -102,7 +102,7 @@ by SWIG when it is parsing the interface:
 <div class="code"><pre>
 SWIG                            Always defined when SWIG is processing a file
 SWIGIMPORTED                    Defined when SWIG is importing a file with <tt>%import</tt>
-SWIG_VERSION                    Hexadecimal number containing SWIG version,
+SWIG_VERSION                    Hexadecimal (binary-coded decimal) number containing SWIG version,
                                 such as 0x010311 (corresponding to SWIG-1.3.11).
 
 SWIGALLEGROCL                   Defined when using Allegro CL