diff --git a/SWIG/Lib/perl5/noembed.h b/SWIG/Lib/perl5/noembed.h
index 3ab90f122..3a4cd4325 100644
--- a/SWIG/Lib/perl5/noembed.h
+++ b/SWIG/Lib/perl5/noembed.h
@@ -1,3 +1,6 @@
+/* Workaround perl5 global namespace pollution. Note that undefining library
+ * functions like fopen will not solve the problem on all platforms as fopen
+ * might be a macro on Windows but not necessarily on other operating systems. */
 #ifdef do_open
   #undef do_open
 #endif