diff --git a/build/config.mk b/build/config.mk
index 4fa5af4d7..5beffcfc1 100644
--- a/build/config.mk
+++ b/build/config.mk
@@ -2,7 +2,7 @@
 #── vi: set noet ft=make ts=8 sw=8 fenc=utf-8 :vi ────────────────────┘
 
 PREFIX = /usr/local
-COSMOCC = .cosmocc/3.9.2
+COSMOCC = .cosmocc/3.9.3
 TOOLCHAIN = $(COSMOCC)/bin/cosmo
 
 CC = $(TOOLCHAIN)cc
@@ -52,5 +52,5 @@ clean:; rm -rf o
 .PHONY: distclean
 distclean:; rm -rf o .cosmocc
 
-.cosmocc/3.9.2:
-	build/download-cosmocc.sh $@ 3.9.2 f4ff13af65fcd309f3f1cfd04275996fb7f72a4897726628a8c9cf732e850193
+.cosmocc/3.9.3:
+	build/download-cosmocc.sh $@ 3.9.3 37cfb39217b980b04dc256dc9a4ae55646c371a1b0e63d5a1e45bed3cc14ceae