diff --git a/test/test_acceptance.ml b/test/test_acceptance.ml
index 7e2466e..14bb5ad 100644
--- a/test/test_acceptance.ml
+++ b/test/test_acceptance.ml
@@ -159,13 +159,21 @@ let () =
        symmetric. What the last case cannot pin, because nothing raylib
        computes without a GL context reads them, is width, height and mipmaps
        against each other. *)
-    if Sys.command "ldconfig -p 2>/dev/null | grep -q libraylib" = 0 then
-      outputs "raylib ffi, headless" "programs/raylib-ffi.flan"
-        "17\n34\n51\n68\n\
-         6\n1\n4\n3\n\
-         7\n13\n17\n2\n4\n3.5\n7.25\n11.5\n13.75\n\
-         1\n1\n1\n1\n7\n\
-         7\n0\n17\n2\n4\n"
+    let raylib_out =
+      "17\n34\n51\n68\n\
+       6\n1\n4\n3\n\
+       7\n13\n17\n2\n4\n3.5\n7.25\n11.5\n13.75\n\
+       1\n1\n1\n1\n7\n\
+       7\n0\n17\n2\n4\n"
+    in
+    if Sys.command "ldconfig -p 2>/dev/null | grep -q libraylib" = 0 then begin
+      outputs "raylib ffi, headless" "programs/raylib-ffi.flan" raylib_out;
+      (* And at -O0, for the reason the rest of the table is: every struct
+         here crosses as (addr v) on a local, which is the alloca mem2reg
+         would launder before anyone noticed it was wrong. *)
+      outputs ~opt:"-O0" "raylib ffi, headless, -O0" "programs/raylib-ffi.flan"
+        raylib_out
+    end
     else
       print_endline "acceptance: skipping the raylib FFI case (no libraylib)";