diff --git a/configure.ac b/configure.ac

--- a/configure.ac

+++ b/configure.ac

@@ -112,6 +112,13 @@ AC_SUBST([JPEG_LIBS])

 AC_DEFINE_UNQUOTED([HAVE_JPEGLIB], $HAVE_JPEGLIB, [Define to 1 if you have libjpeg installed])

 PKG_CHECK_MODULES(SSL, "openssl", [HAVE_OPENSSL=1])

+AC_DEFUN([PKG_CHECK_VAR],

+  [AC_REQUIRE([PKG_PROG_PKG_CONFIG])

+   AC_ARG_VAR([$1], [value of $3 for $2, overriding pkg-config])

+   _PKG_CONFIG([$1], [variable="][$3]["], [$2])

+   AS_VAR_COPY([$1], [pkg_cv_][$1])

+   AS_VAR_IF([$1], [""], [$5], [$4])

+  ])# PKG_CHECK_VAR

 PKG_CHECK_VAR(SSL_PREFIX, "openssl", "exec_prefix",, AC_MSG_ERROR([Could not find exec_prefix for openssl]))

 AC_DEFINE_UNQUOTED([HAVE_OPENSSL], $HAVE_OPENSSL, [Define to 1 if you have OpenSSL installed])

 AC_SUBST(SSL_PREFIX)