diff --git a/src/macroexpand.scm b/src/macroexpand.scm
index c3173423cb53f..b7b3e78c994ce 100644
--- a/src/macroexpand.scm
+++ b/src/macroexpand.scm
@@ -85,6 +85,8 @@
    ;; where
    (pattern-lambda (where ex . vars)
                    (cons 'varlist (typevar-names vars)))
+   (pattern-lambda (= (curly ex . vars) rhs)
+                   (cons 'varlist (typevar-names vars)))
 
    ;; let
    (pattern-lambda (let binds ex)
diff --git a/test/syntax.jl b/test/syntax.jl
index 4b969ab44f619..a90c55b1ef1a7 100644
--- a/test/syntax.jl
+++ b/test/syntax.jl
@@ -1448,3 +1448,12 @@ end
 @test Meta.lower(@__MODULE__, :(Int[ return 0 for i=1:2 ])) == Expr(:error, "\"return\" not allowed inside comprehension or generator")
 @test [ ()->return 42 for i = 1:1 ][1]() == 42
 @test Function[ identity() do x; return 2x; end for i = 1:1 ][1](21) == 42
+
+# issue #27155
+macro test27155()
+    quote
+        MyTest27155{Arg} = Tuple{Arg}
+        MyTest27155
+    end
+end
+@test @test27155() == (Tuple{T} where T)