diff --git a/flang/CMakeLists.txt b/flang/CMakeLists.txt
index 1318eafec7c32..812a794fe3e74 100644
--- a/flang/CMakeLists.txt
+++ b/flang/CMakeLists.txt
@@ -57,7 +57,7 @@ if (CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR)
       CLANG_DIR_ABSOLUTE
       ${CLANG_DIR}
       REALPATH
-      CMAKE_CURRENT_SOURCE_DIR)
+      ${CMAKE_CURRENT_SOURCE_DIR})
     list(APPEND CMAKE_MODULE_PATH ${CLANG_DIR_ABSOLUTE})
 
     # TODO: Remove when libclangDriver is lifted out of Clang