diff --git a/gempyrelib/CMakeLists.txt b/gempyrelib/CMakeLists.txt
index bda03da..575ac7e 100644
--- a/gempyrelib/CMakeLists.txt
+++ b/gempyrelib/CMakeLists.txt
@@ -425,8 +425,8 @@ if(PEDANTIC_WARNINGS)
 endif()
 
 if(DOXYGEN)
-    cmake_path(ABSOLUTE_PATH CMAKEDOC_DIR NORMALIZE OUTPUT_VARIABLE CD_DIR)
-    if (EXISTS "${CD_DIR}")
+    if (DEFINED CMAKEDOC_DIR)
+        cmake_path(ABSOLUTE_PATH CMAKEDOC_DIR NORMALIZE OUTPUT_VARIABLE CD_DIR)
         message("Using local Cmakedoc ${CD_DIR}")
         include("${CD_DIR}/cmakedoc.cmake")
     else()