Fix case sensitivity issue.
diff --git a/CMakeLists.txt b/CMakeLists.txt
index e8b2e0d..2848b06 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -15,7 +15,7 @@ PROJECT(libgit2 C)
CMAKE_MINIMUM_REQUIRED(VERSION 2.6)
# Find required dependencies
-FIND_PACKAGE(zlib REQUIRED)
+FIND_PACKAGE(ZLIB REQUIRED)
INCLUDE_DIRECTORIES(${ZLIB_INCLUDE_DIR} src)
# Try finding openssl