diff --git a/winpr/include/winpr/string.h b/winpr/include/winpr/string.h
index 09b253c33..3da8fc5b9 100644
--- a/winpr/include/winpr/string.h
+++ b/winpr/include/winpr/string.h
@@ -258,7 +258,7 @@ extern "C"
 	 *
 	 * The function does string conversions of any '\0' terminated input string
 	 *
-	 * Supplying len = 0 will return the required size of the buffer in characters.
+	 * Supplying wlen = 0 will return the required size of the buffer in characters.
 	 *
 	 * \warning Supplying a buffer length smaller than required will result in
 	 * platform dependent (=undefined) behaviour!
@@ -276,7 +276,7 @@ extern "C"
 	 * The function does string conversions of any input string of len (or less)
 	 * characters until it reaches the first '\0'.
 	 *
-	 * Supplying len = 0 will return the required size of the buffer in characters.
+	 * Supplying wlen = 0 will return the required size of the buffer in characters.
 	 *
 	 * \warning Supplying a buffer length smaller than required will result in
 	 * platform dependent (=undefined) behaviour!
@@ -295,7 +295,7 @@ extern "C"
 	 * The function does string conversions of any input string of len characters.
 	 * Any character in the buffer (incuding any '\0') is converted.
 	 *
-	 * Supplying len = 0 will return the required size of the buffer in characters.
+	 * Supplying wlen = 0 will return the required size of the buffer in characters.
 	 *
 	 * \warning Supplying a buffer length smaller than required will result in
 	 * platform dependent (=undefined) behaviour!