diff --git a/autoconf/configure.ac b/autoconf/configure.ac
index c9757d9ff7b..6316be9c527 100644
--- a/autoconf/configure.ac
+++ b/autoconf/configure.ac
@@ -1589,7 +1589,7 @@ AC_CONFIG_FILES([docs/doxygen.cfg])
 
 dnl Configure clang, if present
 if test ${clang_src_root} = ""; then
-  clang_src_root="$ac_pwd/tools/clang"
+  clang_src_root="$srcdir/tools/clang"
 fi
 if test -f ${clang_src_root}/README.txt; then
   AC_CONFIG_HEADERS([${clang_src_root}/include/clang/Config/config.h])