diff --git a/pngpriv.h b/pngpriv.h
index 1f2e90f..07349f4 100644
--- a/pngpriv.h
+++ b/pngpriv.h
@@ -917,7 +917,7 @@
     * PNG files the -I directives must match.
     *
     * The most likely explanation is that you passed a -I in CFLAGS. This will
-    * not work; all the preprocessor directories and in particular all the -I
+    * not work; all the preprocessor directives and in particular all the -I
     * directives must be in CPPFLAGS.
     */
 #endif