diff --git a/config/rules.mk b/config/rules.mk
index 09d22548b89e..d253c05d6e68 100644
--- a/config/rules.mk
+++ b/config/rules.mk
@@ -913,8 +913,11 @@ else
 rust_debug_info=2
 endif
 
+# We use the + prefix to pass down the jobserver fds to cargo, but we
+# don't use the prefix when make -n is used, so that cargo doesn't run
+# in that case)
 define RUN_CARGO
-env $(environment_cleaner) $(rust_unlock_unstable) $(rustflags_override) $(sccache_wrap) \
+$(if $(findstring n,$(filter-out --%, $(MAKEFLAGS))),,+)env $(environment_cleaner) $(rust_unlock_unstable) $(rustflags_override) $(sccache_wrap) \
 	CARGO_TARGET_DIR=$(CARGO_TARGET_DIR) \
 	RUSTC=$(RUSTC) \
 	RUSTFLAGS='-C debuginfo=$(rust_debug_info)' \