diff --git a/cmake/git_utils.cmake b/cmake/git_utils.cmake
index 2e2645c37..ba14c5c2b 100644
--- a/cmake/git_utils.cmake
+++ b/cmake/git_utils.cmake
@@ -38,8 +38,8 @@ function(add_git_dir_dependency GIT_DOT_FILE SUCCESS_VAR)
         get_filename_component(GIT_WORKTREE_PARENT "${GIT_WORKTREE_PARENT}" NAME)
         if ("${GIT_WORKTREE_PARENT}" STREQUAL "modules")
           # Z3 is a git submodule
-          set(GIT_HEAD_FILE "${CMAKE_SOURCE_DIR}/${GIT_HEAD_FILE}")
-          set(GIT_DIR "${CMAKE_SOURCE_DIR}/${GIT_WORKTREE_DIR}")
+          set(GIT_HEAD_FILE "${Z3_SOURCE_DIR}/${GIT_HEAD_FILE}")
+          set(GIT_DIR "${Z3_SOURCE_DIR}/${GIT_WORKTREE_DIR}")
         else()
           message(FATAL_ERROR "Found git worktree dir but could not find \"${GIT_COMMON_DIR_FILE}\"")
         endif()