diff --git a/Adafruit_PN532.cpp b/Adafruit_PN532.cpp
index 737659d..7b4b282 100644
--- a/Adafruit_PN532.cpp
+++ b/Adafruit_PN532.cpp
@@ -1059,7 +1059,7 @@ uint8_t Adafruit_PN532::mifareclassic_WriteNDEFURI(uint8_t sectorNumber,
     // Url fits in three blocks
     memcpy(sectorbuffer1 + 9, url, 7);
     memcpy(sectorbuffer2, url + 7, 16);
-    memcpy(sectorbuffer3, url + 23, len - 24);
+    memcpy(sectorbuffer3, url + 23, len - 23);
     sectorbuffer3[len - 22] = 0xFE;
   }