Fix broken sec1 url in README
diff --git a/README.md b/README.md
index 21e1844..fd31d1c 100644
--- a/README.md
+++ b/README.md
@@ -19,7 +19,7 @@
 Usage Notes
 -----------
 ### Point Representation ###
-Compressed points are represented in the standard format as defined in http://www.secg.org/collateral/sec1_final.pdf; uncompressed points are represented in standard format, but without the `0x04` prefix. All functions except `uECC_compress()` only accept uncompressed points; use `uECC_compress()` and `uECC_decompress()` to convert between compressed and uncompressed point representations.
+Compressed points are represented in the standard format as defined in http://www.secg.org/sec1-v2.pdf; uncompressed points are represented in standard format, but without the `0x04` prefix. All functions except `uECC_compress()` only accept uncompressed points; use `uECC_compress()` and `uECC_decompress()` to convert between compressed and uncompressed point representations.
 
 Private keys are represented in the standard format.