diff --git a/pkgs/development/compilers/rust/cargo.nix b/pkgs/development/compilers/rust/cargo.nix
index a86e4a3d186d..3fb4f948a223 100644
--- a/pkgs/development/compilers/rust/cargo.nix
+++ b/pkgs/development/compilers/rust/cargo.nix
@@ -80,9 +80,9 @@ rustPlatform.buildRustPackage.override
       if stdenv.buildPlatform.canExecute stdenv.hostPlatform then
         ''
           installShellCompletion --cmd cargo \
-            --bash <(CARGO_COMPLETE=bash cargo) \
-            --fish <(CARGO_COMPLETE=fish cargo) \
-            --zsh <(CARGO_COMPLETE=zsh cargo)
+            --bash <(CARGO_COMPLETE=bash $out/bin/cargo) \
+            --fish <(CARGO_COMPLETE=fish $out/bin/cargo) \
+            --zsh <(CARGO_COMPLETE=zsh $out/bin/cargo)
         ''
       else
         ''
@@ -109,6 +109,13 @@ rustPlatform.buildRustPackage.override
       runHook postInstallCheck
     '';
 
+    # Make sure our build rustc/cargo never make it into our runtime closure
+    disallowedReferences = [
+      rustPlatform.rust.cargo
+      rustPlatform.rust.rustc
+      rustPlatform.rust.rustc.unwrapped
+    ];
+
     meta = {
       homepage = "https://crates.io";
       description = "Downloads your Rust project's dependencies and builds your project";
diff --git a/pkgs/development/compilers/rust/make-rust-platform.nix b/pkgs/development/compilers/rust/make-rust-platform.nix
index 1f69bb92e213..254ae918bbf6 100644
--- a/pkgs/development/compilers/rust/make-rust-platform.nix
+++ b/pkgs/development/compilers/rust/make-rust-platform.nix
@@ -72,14 +72,16 @@
         maturinBuildHook
         bindgenHook
         ;
+
+      # Let packages reference the build derivations, e.g. for disallowedReferences.
+      # Get rid of the splicing though, so `nativeBuildInputs = [ rustPlatform.rust.rustc ]` works.
+      rust = {
+        rustc = rustc.__spliced.hostTarget or rustc;
+        cargo = cargo.__spliced.hostTarget or cargo;
+      };
     };
 })
 // lib.optionalAttrs config.allowAliases {
-  rust = {
-    rustc = lib.warn "rustPlatform.rust.rustc is deprecated. Use rustc instead." rustc;
-    cargo = lib.warn "rustPlatform.rust.cargo is deprecated. Use cargo instead." cargo;
-  };
-
   # Added in 25.05.
   fetchCargoTarball = throw "`rustPlatform.fetchCargoTarball` has been removed in 25.05, use `rustPlatform.fetchCargoVendor` instead";
 }
diff --git a/pkgs/development/compilers/rust/rustc.nix b/pkgs/development/compilers/rust/rustc.nix
index cf86b5412571..f5c09e0740ba 100644
--- a/pkgs/development/compilers/rust/rustc.nix
+++ b/pkgs/development/compilers/rust/rustc.nix
@@ -448,6 +448,12 @@ stdenv.mkDerivation (finalAttrs: {
 
   requiredSystemFeatures = [ "big-parallel" ];
 
+  # Make sure our bootstrap packages don't end up in our runtime closure
+  disallowedReferences = [
+    cargo
+    rustc
+  ];
+
   passthru = {
     llvm = llvmShared;
     inherit llvmPackages;