diff --git a/fuzzers/Makefile b/fuzzers/Makefile
index d98c3ec6..5405869e 100644
--- a/fuzzers/Makefile
+++ b/fuzzers/Makefile
@@ -72,7 +72,8 @@ $(eval $(call fuzzer,028-fifo-config,005-tilegrid))
 $(eval $(call fuzzer,029-bram-fifo-config,005-tilegrid))
 $(eval $(call fuzzer,040-clk-hrow-config,005-tilegrid))
 $(eval $(call fuzzer,041-clk-hrow-pips,005-tilegrid))
-$(eval $(call fuzzer,042-clk-bufg-config,005-tilegrid))
+# 042 fuzzer is unstable, issue #657
+#$(eval $(call fuzzer,042-clk-bufg-config,005-tilegrid))
 $(eval $(call fuzzer,043-clk-rebuf-pips,005-tilegrid))
 $(eval $(call fuzzer,050-pip-seed,005-tilegrid))
 $(eval $(call fuzzer,051-pip-imuxlout-bypalts,050-pip-seed))