diff --git a/configure.ac b/configure.ac
index 4f14ebd0..9189c94e 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1215,7 +1215,7 @@ AC_SUBST([TEST_CFLAGS])
 # needed for unit testing
 AC_CHECK_PROGS([CMAKE], [cmake])
 if test -n "${CMAKE}"; then
-   if test -f vendor/cmocka/CMakeLists.txt; then
+   if test -f "${srcdir}/vendor/cmocka/CMakeLists.txt"; then
       AM_CONDITIONAL([CMOCKA_INITIALIZED], [true])
    else
       AM_CONDITIONAL([CMOCKA_INITIALIZED], [false])