diff --git a/configure.ac b/configure.ac
index f63eb870ffb..e406863178d 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1664,7 +1664,7 @@ AC_ARG_ENABLE([gcc-warnings],
    # however, if there is also a .tarball-version file it is probably
    # just a release imported into Git for patch management.
    gl_gcc_warnings=no
-   if test -e "$srcdir"/.git && test ! -f "$srcdir"/.tarball-version; then
+   if test -d "$srcdir"/.git -o -f "$srcdir"/.git && test ! -f "$srcdir"/.tarball-version; then
       # Clang typically identifies itself as GCC 4.2 or something similar
       # even if it is recent enough to accept the warnings we enable.
       AS_IF([test "$emacs_cv_clang" = yes],