diff --git a/mk/prefix.mk b/mk/prefix.mk
index b25ad57a1..c0e790e8f 100644
--- a/mk/prefix.mk
+++ b/mk/prefix.mk
@@ -9,8 +9,7 @@ GNU_HOST=$(HOST_ARCH)-unknown-linux-gnu
 BINUTILS_BRANCH=redox-2.43.1
 GCC_BRANCH=redox-13.2.0
 LIBTOOL_VERSION=2.5.4
-# nightly a day after 1.89 release
-UPSTREAM_RUSTC_VERSION="2025-08-09"
+UPSTREAM_RUSTC_VERSION="2025-10-03"
 
 export PREFIX_RUSTFLAGS=-L $(ROOT)/$(PREFIX_INSTALL)/$(TARGET)/lib
 export RUSTUP_TOOLCHAIN=$(ROOT)/$(PREFIX_INSTALL)