diff --git a/tests/blif/generate_mk.py b/tests/blif/generate_mk.py
index 47cb9accd..bd6d74fd9 100644
--- a/tests/blif/generate_mk.py
+++ b/tests/blif/generate_mk.py
@@ -7,5 +7,5 @@ import gen_tests_makefile
 
 gen_tests_makefile.generate(["--yosys-scripts"], [],
 """[ ! -f $(@:.ys=.blif) ] || \\
-    diff <(tail -n +2 $(@:.ys=.blif).out) <(tail -n +2 $(@:.ys=.blif).ok) >/dev/null 2>&1 || exit 1; \\
+    sed '1d' $(@:.ys=.blif).out | diff - <(sed '1d' $(@:.ys=.blif).ok) >/dev/null 2>&1 || exit 1; \\
 """)
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