diff --git a/src/jsx.erl b/src/jsx.erl
index 953abb8..1e7ded9 100644
--- a/src/jsx.erl
+++ b/src/jsx.erl
@@ -82,15 +82,15 @@ minify(Source) -> format(Source, []).
 prettify(Source) -> format(Source, [space, {indent, 2}]).
 
 
--spec is_json(Source::any()) -> true | false.
--spec is_json(Source::any(), Config::jsx_verify:config()) -> true | false.
+-spec is_json(Source::any()) -> true | false | {incomplete, decoder()}.
+-spec is_json(Source::any(), Config::jsx_verify:config()) -> true | false | {incomplete, decoder()}.
 
 is_json(Source) -> is_json(Source, []).
 is_json(Source, Config) -> jsx_verify:is_json(Source, Config).
 
 
--spec is_term(Source::any()) -> true | false.
--spec is_term(Source::any(), Config::jsx_verify:config()) -> true | false.
+-spec is_term(Source::any()) -> true | false | {incomplete, encoder()}.
+-spec is_term(Source::any(), Config::jsx_verify:config()) -> true | false | {incomplete, encoder()}.
 
 is_term(Source) -> is_term(Source, []).
 is_term(Source, Config) -> jsx_verify:is_term(Source, Config).
diff --git a/src/jsx_verify.erl b/src/jsx_verify.erl
index e923691..09a668d 100644
--- a/src/jsx_verify.erl
+++ b/src/jsx_verify.erl
@@ -35,7 +35,7 @@
 -export_type([config/0]).
 
 
--spec is_json(Source::binary(), Config::config()) -> true | false.
+-spec is_json(Source::binary(), Config::config()) -> true | false | {incomplete, jsx:decoder()}.
 
 is_json(Source, Config) when is_list(Config) ->
     try (jsx:decoder(?MODULE, Config, jsx_config:extract_config(Config)))(Source)
@@ -43,7 +43,7 @@ is_json(Source, Config) when is_list(Config) ->
     end.
 
 
--spec is_term(Source::any(), Config::config()) -> true | false.
+-spec is_term(Source::any(), Config::config()) -> true | false | {incomplete, jsx:encoder()}.
 
 is_term(Source, Config) when is_list(Config) ->
     try (jsx:encoder(?MODULE, Config, jsx_config:extract_config(Config)))(Source)