diff --git a/src/bootstrap/config.rs b/src/bootstrap/config.rs
index bd962ecb2faf1..276b544b7ba87 100644
--- a/src/bootstrap/config.rs
+++ b/src/bootstrap/config.rs
@@ -1516,7 +1516,7 @@ impl Config {
                 }
                 if let Some(patches) = cfg.llvm_has_rust_patches {
                     assert!(
-                        config.submodules.is_some(),
+                        config.submodules.is_none(),
                         "cannot set `llvm-has-rust-patches` for a managed submodule"
                     );
                     target.llvm_has_rust_patches = Some(patches);