diff --git a/CMakeLists.txt b/CMakeLists.txt
index bbd57a9fe..ae7c9eb1d 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -22,7 +22,7 @@ project(ncnn)
 option(NCNN_OPENMP "openmp support" ON)
 option(NCNN_STDIO "load model from external file" ON)
 option(NCNN_STRING "plain and verbose string" ON)
-option(NCNN_INSTALL_SDK "Install ncnn library and headers" ON)
+option(NCNN_INSTALL_SDK "install ncnn library and headers" ON)
 option(NCNN_OPENCV "minimal opencv structure emulation" OFF)
 option(NCNN_BENCHMARK "print benchmark information for every layer" OFF)
 option(NCNN_PIXEL "convert and resize from/to image pixel" ON)