diff --git a/pngpriv.h b/pngpriv.h
index 138505a..2e70a87 100644
--- a/pngpriv.h
+++ b/pngpriv.h
@@ -338,8 +338,11 @@
  * default is just to use PNG_LIBPNG_BUILD_BASE_TYPE.  Set this in CPPFLAGS
  * with either:
  *
- *   -DPNG_RELEASE_BUILD=1 Turns on the release compile path
+ *   -DPNG_RELEASE_BUILD Turns on the release compile path
  *   -DPNG_RELEASE_BUILD=0 Turns it off
+ * or in your pngusr.h with
+ *   #define PNG_RELEASE_BUILD=1 Turns on the release compile path
+ *   #define PNG_RELEASE_BUILD=0 Turns it off
  */
 #ifndef PNG_RELEASE_BUILD
 #  define PNG_RELEASE_BUILD (PNG_LIBPNG_BUILD_BASE_TYPE >= PNG_LIBPNG_BUILD_RC)