diff --git a/lib/spack/spack/util/unparse/unparser.py b/lib/spack/spack/util/unparse/unparser.py
index a8dc88c8ce4..a657281a3e0 100644
--- a/lib/spack/spack/util/unparse/unparser.py
+++ b/lib/spack/spack/util/unparse/unparser.py
@@ -1261,6 +1261,10 @@ def visit_MatchOr(self, node):
     def visit_TypeAlias(self, node):
         self.fill("type ")
         self.dispatch(node.name)
+        if node.type_params:
+            self.write("[")
+            interleave(lambda: self.write(", "), self.dispatch, node.type_params)
+            self.write("]")
         self.write(" = ")
         self.dispatch(node.value)