diff --git a/Dockerfile.system-clang b/Dockerfile.system-clang
index c8091d0..58d82d9 100644
--- a/Dockerfile.system-clang
+++ b/Dockerfile.system-clang
@@ -22,7 +22,8 @@ WORKDIR /build
 
 ENV TOOLCHAIN_PREFIX=/opt/llvm-mingw
 
-ARG TOOLCHAIN_ARCHS="i686 x86_64 armv7 aarch64 arm64ec"
+# arm64ec requires Clang/LLD 21
+ARG TOOLCHAIN_ARCHS="i686 x86_64 armv7 aarch64"
 
 ARG DEFAULT_CRT=ucrt