diff --git a/package/pkg-cmake.mk b/package/pkg-cmake.mk
index 6739704e3c..14ffe4a88f 100644
--- a/package/pkg-cmake.mk
+++ b/package/pkg-cmake.mk
@@ -80,6 +80,14 @@ ifndef $(2)_CONFIGURE_CMDS
 ifeq ($(4),target)
 
 # Configure package for target
+#
+# - We are passing BUILD_SHARED_LIBS because it is documented as a
+#   standard CMake variable to control the build of shared libraries
+#   (see https://cmake.org/cmake/help/v3.8/manual/cmake-variables.7.html#variables-that-change-behavior)
+# - We are not passing BUILD_STATIC_LIBS because it is *not*
+#   documented as a standard CMake variable. If a package supports it,
+#   it must handle it explicitly.
+#
 define $(2)_CONFIGURE_CMDS
 	(mkdir -p $$($$(PKG)_BUILDDIR) && \
 	cd $$($$(PKG)_BUILDDIR) && \