diff --git a/tests/functional/flakes/dubious-query.sh b/tests/functional/flakes/dubious-query.sh
new file mode 100644
index 000000000000..00ddc9891dbc
--- /dev/null
+++ b/tests/functional/flakes/dubious-query.sh
@@ -0,0 +1,37 @@
+#!/usr/bin/env bash
+
+source ./common.sh
+
+requireGit
+clearStoreIfPossible
+
+nixpkgsDir="$TEST_ROOT/nixpkgs"
+createGitRepo "$nixpkgsDir"
+createSimpleGitFlake "$nixpkgsDir"
+nix registry add --registry "$registry" nixpkgs "git+file://$nixpkgsDir"
+
+fooDrvPath="$(nix eval --raw "git+file://$nixpkgsDir#foo" --apply '(e: e.drvPath)')"
+
+# Check that a flakeref without a query is accepted correctly.
+assertStderr "nix build --dry-run git+file://$nixpkgsDir#foo" <<EOF
+this derivation will be built:
+  $fooDrvPath
+EOF
+
+# Check that a flakeref with a good query is accepted correctly.
+assertStderr "nix build --dry-run git+file://$nixpkgsDir?foo=bar#foo" <<EOF
+this derivation will be built:
+  $fooDrvPath
+EOF
+
+# Check that we get the dubious query warning, when passing in a query without an equal sign.
+assertStderr "nix build --dry-run git+file://$nixpkgsDir?bar#foo" <<EOF
+warning: dubious URI query 'bar' is missing equal sign '='
+this derivation will be built:
+  $fooDrvPath
+EOF
+
+# Check that the anchor (#) is taken as a whole, and not split.
+assertStderr "nix build --dry-run git+file://$nixpkgsDir#foo?bar" <<EOF
+error: flake 'git+file://$nixpkgsDir' does not provide attribute 'packages.$system.foo?bar', 'legacyPackages.$system.foo?bar' or 'foo?bar'
+EOF
diff --git a/tests/functional/flakes/local.mk b/tests/functional/flakes/local.mk
index 71e50ad073fc..a37840240f96 100644
--- a/tests/functional/flakes/local.mk
+++ b/tests/functional/flakes/local.mk
@@ -19,6 +19,7 @@ flake-tests := \
   $(d)/eval-cache.sh \
   $(d)/search-root.sh \
   $(d)/config.sh \
-  $(d)/show.sh
+  $(d)/show.sh \
+  $(d)/dubious-query.sh
 
 install-tests-groups += flake
diff --git a/tests/functional/flakes/meson.build b/tests/functional/flakes/meson.build
index 8c1afd6ff051..4f455fcce7b9 100644
--- a/tests/functional/flakes/meson.build
+++ b/tests/functional/flakes/meson.build
@@ -23,6 +23,7 @@ suites += {
     'search-root.sh',
     'config.sh',
     'show.sh',
+    'dubious-query.sh',
   ],
   'workdir': meson.current_build_dir(),
 }