diff --git a/configure.ac b/configure.ac
index 3e7066d..f232078 100644
--- a/configure.ac
+++ b/configure.ac
@@ -51,8 +51,8 @@ if test "${enable_x11}" = "yes"; then
   AC_PATH_X
   AC_CHECK_LIB(X11, XOpenDisplay,
    [ac_cv_my_have_x11=yes
-    X_CFLAGS="-I${x_includes}"
-    X_LIBS="-lX11 -L${x_libraries}"],
+    if test -n "${x_includes}"; then X_CFLAGS="-I${x_includes}"; fi
+    if test -n "${x_libraries}"; then X_LIBS="-lX11 -L${x_libraries}"; fi],
    [ac_cv_my_have_x11=no],
    [[-lXt -L${x_libraries}]])
   if test "${ac_cv_my_have_x11}" != "yes"; then
diff --git a/debian/control b/debian/control
index 80585ef..7e75c17 100644
--- a/debian/control
+++ b/debian/control
@@ -8,7 +8,7 @@ Standards-Version: 3.6.1.0
 Package: libcaca-dev
 Section: libdevel
 Architecture: any
-Depends: ${shlibs:Depends}, libncurses5-dev
+Depends: ${shlibs:Depends}, libncurses5-dev, slang1-dev, xlibs-dev
 Description: text mode graphics library
  libcaca is the Colour AsCii Art library. It provides high level functions
  for colour text drawing, simple primitives for line, polygon and ellipse