diff --git a/base/docs/Docs.jl b/base/docs/Docs.jl
index 63672a90941ad..9988ed016d7ff 100644
--- a/base/docs/Docs.jl
+++ b/base/docs/Docs.jl
@@ -326,7 +326,7 @@ end
 doc(f::Base.Callable, args::Any...) = doc(f, Tuple{args...})
 
 function typesummary(T::DataType)
-    parts = [
+    parts = UTF8String[
     """
     **Summary:**
     ```julia
diff --git a/test/docs.jl b/test/docs.jl
index 52b0b84ced72a..5bd3c47073d8d 100644
--- a/test/docs.jl
+++ b/test/docs.jl
@@ -318,6 +318,9 @@ end
 
 @test isdefined(MacroGenerated, :_g)
 
+# Issue #13385.
+@test @doc(I) !== nothing
+
 # Issue #12700.
 @test @doc(DocsTest.@m) == doc"Inner.@m"