diff --git a/apps/common/lib/lexical/ast/analysis.ex b/apps/common/lib/lexical/ast/analysis.ex
index 14e19d032..35e4c0d72 100644
--- a/apps/common/lib/lexical/ast/analysis.ex
+++ b/apps/common/lib/lexical/ast/analysis.ex
@@ -333,7 +333,7 @@ defmodule Lexical.Ast.Analysis do
     end
   end
 
-  defp fetch_alias_as(options) do
+  defp fetch_alias_as(options) when is_list(options) do
     alias_as =
       Enum.find_value(options, fn
         {{:__block__, _, [:as]}, {:__aliases__, _, [alias_as]}} -> alias_as
@@ -345,4 +345,9 @@ defmodule Lexical.Ast.Analysis do
       _ -> {:ok, alias_as}
     end
   end
+
+  # When the `as` section is incomplete, like: `alias Foo, a`
+  defp fetch_alias_as(_) do
+    :error
+  end
 end
diff --git a/apps/common/test/lexical/ast_test.exs b/apps/common/test/lexical/ast_test.exs
index 93b46f2e7..05d70e913 100644
--- a/apps/common/test/lexical/ast_test.exs
+++ b/apps/common/test/lexical/ast_test.exs
@@ -296,6 +296,17 @@ defmodule Lexical.AstTest do
       refute analysis.ast
       assert {:error, _} = analysis.parse_error
     end
+
+    test "creates an analysis from a document with incomplete `as` section" do
+      code = ~q[
+        defmodule Invalid do
+          alias Foo, a
+        end
+      ]
+
+      assert %Analysis{} = analysis = analyze(code)
+      assert {:defmodule, _, _} = analysis.ast
+    end
   end
 
   defp ast(s) do