Fix typo in option description.
diff --git a/CMakeLists.txt b/CMakeLists.txt
index f4e519e..1a9f0ed 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -7,7 +7,7 @@
 
 PROJECT(libzip C)
 
-OPTION(ENABLE_GNUTLS "Enable use of GNuTLS" ON)
+OPTION(ENABLE_GNUTLS "Enable use of GnuTLS" ON)
 OPTION(ENABLE_OPENSSL "Enable use of OpenSSL" ON)
 OPTION(ENABLE_COMMONCRYPTO "Enable use of CommonCrypto" ON)