diff --git a/pkgs/development/compilers/swift/sourcekit-lsp/default.nix b/pkgs/development/compilers/swift/sourcekit-lsp/default.nix
index bff1b9a8f0e9..deb82de20add 100644
--- a/pkgs/development/compilers/swift/sourcekit-lsp/default.nix
+++ b/pkgs/development/compilers/swift/sourcekit-lsp/default.nix
@@ -58,6 +58,10 @@ stdenv.mkDerivation {
     cp $binPath/sourcekit-lsp $out/bin/
   '';
 
+  # Canary to verify output of our Swift toolchain does not depend on the Swift
+  # compiler itself. (Only its 'lib' output.)
+  disallowedRequisites = [ swift.swift ];
+
   meta = {
     description = "Language Server Protocol implementation for Swift and C-based languages";
     homepage = "https://github.com/apple/sourcekit-lsp";
diff --git a/pkgs/development/compilers/swift/swift-docc/default.nix b/pkgs/development/compilers/swift/swift-docc/default.nix
index 6f0615fe1935..f85512f84071 100644
--- a/pkgs/development/compilers/swift/swift-docc/default.nix
+++ b/pkgs/development/compilers/swift/swift-docc/default.nix
@@ -39,6 +39,10 @@ stdenv.mkDerivation {
     ln -s $renderArtifact/dist $out/share/docc/render
   '';
 
+  # Canary to verify output of our Swift toolchain does not depend on the Swift
+  # compiler itself. (Only its 'lib' output.)
+  disallowedRequisites = [ swift.swift ];
+
   meta = {
     description = "Documentation compiler for Swift";
     homepage = "https://github.com/apple/swift-docc";