diff --git a/configure.ac b/configure.ac
index 1238f5e..86085ea 100644
--- a/configure.ac
+++ b/configure.ac
@@ -389,12 +389,16 @@ CAIRO_ENABLE_FUNCTIONS(egl, EGL, auto, [
 
 CAIRO_ENABLE_FUNCTIONS(glx, GLX, auto, [
   if test "x$need_glx_functions" = "xyes"; then
+    if test "x$use_gl" != "xyes"; then
+        use_glx="no (gl backend missing)"
+    else
     save_CFLAGS="$CFLAGS"
     CFLAGS="$CFLAGS $gl_CFLAGS $gl_NONPKGCONFIG_CFLAGS"
     AC_CHECK_HEADER(GL/glx.h,, [use_glx="no (GLX headers not found)"])
     glx_NONPKGCONFIG_CFLAGS=
     glx_NONPKGCONFIG_LIBS="-lGL"
     CFLAGS="$save_CFLAGS"
+    fi
   else
       use_glx="no (not required by any backend)"
   fi