diff --git a/common/hw-gfx-gma-config.ads.template b/common/hw-gfx-gma-config.ads.template
index d5bd2ba..e4e557a 100644
--- a/common/hw-gfx-gma-config.ads.template
+++ b/common/hw-gfx-gma-config.ads.template
@@ -322,7 +322,10 @@
 
    -- FIXME: Unknown for Broxton, Linux' i915 contains a fixme too :-D
    HDMI_Max_Clock_24bpp : constant Frequency_Type :=
-     (if Haswell_On then 300_000_000 else 225_000_000);
+     (case Gen is
+         when Generation'First .. G45     => 165_000_000,
+         when Ironlake                    => 225_000_000,
+         when Haswell .. Generation'Last  => 300_000_000);
 
    ----------------------------------------------------------------------------