--- a/lib/HTML/Clean.pm
+++ b/lib/HTML/Clean.pm
@@ -366,6 +366,16 @@ The following options are recognized:
 
 =back
 
+Please note that if your HTML includes preformatted regions (this means, if
+it includes <pre>...</pre>, we do not suggest removing whitespace, as it will
+alter the rendered defaults.
+
+HTML::Clean will print out a warning if it finds a preformatted region and is
+requested to strip whitespace. In order to prevent this, specify that you don't
+want to strip whitespace - i.e.
+
+  $h->strip( {whitespace => 0} );
+
 =cut
 
 use vars qw/
@@ -426,6 +436,17 @@ sub strip {
   }
 
   if ($do_whitespace) {
+    if ($$h =~ /<pre/i) {
+      warn << 'EOF'
+Warning: Stripping whitespace will affect preformatted region\'s layout
+You have a <pre> region in your HTML, which depends on the whitespace not
+being modified. You requested to strip the whitespace - The rendered results
+will be affected.
+
+Hint: Use $h->strip({whitespace => 0}); instead.
+EOF
+    }
+
     $$h =~ s,[\r\n]+,\n,sg; # Carriage/LF -> LF
     $$h =~ s,\s+\n,\n,sg;   # empty line
     $$h =~ s,\n\s+<,\n<,sg; # space before tag