diff --git a/cmake/CMakeLists.txt b/cmake/CMakeLists.txt
index e439fd49..bbeaf021 100644
--- a/cmake/CMakeLists.txt
+++ b/cmake/CMakeLists.txt
@@ -43,8 +43,18 @@
 cmake_minimum_required(VERSION 3.12)
 project(glad C)
 
-set(GLAD_CMAKE_DIR "${CMAKE_CURRENT_LIST_DIR}" CACHE STRING "Directory containing glad generator CMakeLists.txt")
-set(GLAD_SOURCES_DIR "${GLAD_CMAKE_DIR}/../"   CACHE STRING "Directory containing glad sources (python modules), used as working directory")
+set(
+    GLAD_CMAKE_DIR 
+    "${CMAKE_CURRENT_LIST_DIR}" 
+    CACHE STRING 
+    "Directory containing glad generator CMakeLists.txt. Must be absolute."
+    )
+set(
+    GLAD_SOURCES_DIR 
+    "${GLAD_CMAKE_DIR}/../"   
+    CACHE STRING 
+    "Directory containing glad sources (python modules), used as working directory. Must be absolute."
+    )
 mark_as_advanced(GLAD_CMAKE_DIR)
 
 # Extract specification, profile and version from a string