diff --git a/index/li/libx11/libx11-external.toml b/index/li/libx11/libx11-external.toml
index 0933be5e..56abfac1 100644
--- a/index/li/libx11/libx11-external.toml
+++ b/index/li/libx11/libx11-external.toml
@@ -7,4 +7,5 @@ maintainers-logins = ["mosteo"]
 [[external]]
 kind = "system"
 [external.origin."case(distribution)"]
+"arch" = ["libx11"]
 "debian|ubuntu" = ["libx11-dev"]
diff --git a/index/op/openglada/openglada-0.6.0.toml b/index/op/openglada/openglada-0.6.0.toml
index 184aae46..dd8ac353 100644
--- a/index/op/openglada/openglada-0.6.0.toml
+++ b/index/op/openglada/openglada-0.6.0.toml
@@ -10,16 +10,20 @@ maintainers-logins = ["flyx"]
 project-files = ["opengl.gpr", "opengl-glfw.gpr", "opengl-soil.gpr", "opengl-test.gpr"]
 
 [[depends-on]]
+gnat = "<8"
 [depends-on."case(os)".linux]
 libglfw3 = "^3"
-libx11 = "^2"
+libx11 = "^1"
 
 [gpr-externals]
 Auto_Exceptions = ["enabled", "disabled"]
 GLFW_Version = ["2", "3"]
 Mode = ["debug", "release"]
-[gpr-set-externals."case(os)".linux]
-Windowing_System = "x11"
+
+[gpr-set-externals."case(os)"]
+linux = { Windowing_System = "x11" }
+macos = { Windowing_System = "quartz" }
+windows = { Windowing_System = "windows" }
 
 [origin]
 url = "https://github.com/flyx/OpenGLAda/archive/v0.6.tar.gz"