diff --git a/src/tiff/tif_lzw.c b/src/tiff/tif_lzw.c
index 663b216c53..d739e6f18d 100644
--- a/src/tiff/tif_lzw.c
+++ b/src/tiff/tif_lzw.c
@@ -36,7 +36,7 @@
  *
  * The original Berkeley copyright notice appears below in its entirety.
  */
-// Watcom C++ (or its make utility) doesn't like long filenames
+/* Watcom C++ (or its make utility) doesn't like long filenames */
 #ifdef __WATCOMC__
 #include "tif_pred.h"
 #else
diff --git a/src/tiff/tif_pixarlog.c b/src/tiff/tif_pixarlog.c
index 668508710e..1cf49be837 100644
--- a/src/tiff/tif_pixarlog.c
+++ b/src/tiff/tif_pixarlog.c
@@ -84,7 +84,7 @@
  * 
  */
 
-// Watcom C++ (or its make utility) doesn't like long filenames
+/* Watcom C++ (or its make utility) doesn't like long filenames */
 #ifdef __WATCOMC__
 #include "tif_pred.h"
 #else
diff --git a/src/tiff/tif_predict.c b/src/tiff/tif_predict.c
index 2e67281233..137a2fb3a4 100644
--- a/src/tiff/tif_predict.c
+++ b/src/tiff/tif_predict.c
@@ -30,7 +30,7 @@
  * Predictor Tag Support (used by multiple codecs).
  */
 #include "tiffiop.h"
-// Watcom C++ (or its make utility) doesn't like long filenames
+/* Watcom C++ (or its make utility) doesn't like long filenames */
 #ifdef __WATCOMC__
 #include "tif_pred.h"
 #else
diff --git a/src/tiff/tif_zip.c b/src/tiff/tif_zip.c
index 2099dc8623..38e98a96c8 100644
--- a/src/tiff/tif_zip.c
+++ b/src/tiff/tif_zip.c
@@ -46,7 +46,7 @@
  * directory ftp://ftp.uu.net/pub/archiving/zip/doc.  The library was
  * last found at ftp://ftp.uu.net/pub/archiving/zip/zlib/zlib-0.99.tar.gz.
  */
-// Watcom C++ (or its make utility) doesn't like long filenames
+/* Watcom C++ (or its make utility) doesn't like long filenames */
 #ifdef __WATCOMC__
 #include "tif_pred.h"
 #else