diff --git a/spec/runtime/document_spec.cc b/spec/runtime/document_spec.cc
index 13041eb4..d9337dc0 100644
--- a/spec/runtime/document_spec.cc
+++ b/spec/runtime/document_spec.cc
@@ -6,82 +6,113 @@ extern "C" const TSLanguage * ts_language_json();
 
 START_TEST
 
-describe("incremental parsing", [&]() {
-    TSDocument *doc;
+describe("Document", [&]() {
+  TSDocument *doc;
+
+  before_each([&]() {
+    doc = ts_document_make();
+  });
+
+  after_each([&]() {
+    ts_document_free(doc);
+  });
+
+  describe("when the language is not set", [&]() {
+    describe("setting the input", [&]() {
+      SpyReader *reader;
+
+      before_each([&]() {
+        reader = new SpyReader("{ \"key\": [1, 2] }", 5);
+        ts_document_set_input(doc, reader->input);
+      });
+
+      after_each([&]() {
+        delete reader;
+      });
+
+      it("does not try to parse the document", [&]() {
+        AssertThat(ts_document_root_node(doc), Equals<TSNode *>(nullptr));
+      });
+
+      describe("setting the language", [&]() {
+        before_each([&]() {
+          ts_document_set_language(doc, ts_language_json());
+        });
+
+        it("parses the document", [&]() {
+          TSNode *node = ts_document_root_node(doc);
+          AssertThat(string(ts_node_string(node)), Equals(
+              "(object (string) (array (number) (number)))"));
+          ts_node_release(node);
+        });
+      });
+    });
+  });
+
+  describe("setting the language and input", [&]() {
+    SpyReader *reader;
 
     before_each([&]() {
-        doc = ts_document_make();
-        ts_document_set_language(doc, ts_language_json());
+      reader = new SpyReader("{ \"key\": [1, 2] }", 5);
+      ts_document_set_language(doc, ts_language_json());
+      ts_document_set_input(doc, reader->input);
     });
 
     after_each([&]() {
-        ts_document_free(doc);
+      delete reader;
     });
 
-    describe("incremental parsing", [&]() {
-        SpyReader *reader;
-
-        before_each([&]() {
-            reader = new SpyReader("{ \"key\": [1, 2] }", 5);
-            ts_document_set_input(doc, reader->input);
-        });
-
-        after_each([&]() {
-            delete reader;
-        });
-
-        it("parses the input", [&]() {
-            AssertThat(string(ts_document_string(doc)), Equals(
-                "(object (string) (array (number) (number)))"));
-        });
-
-        it("reads the entire input", [&]() {
-            AssertThat(reader->strings_read, Equals(vector<string>({
-                "{ \"key\": [1, 2] }"
-            })));
-        });
-
-        describe("modifying the end of the input", [&]() {
-            before_each([&]() {
-                size_t position(string("{ \"key\": [1, 2]").length());
-                string inserted_text(", \"key2\": 4");
-
-                reader->content.insert(position, inserted_text);
-                ts_document_edit(doc, { position, 0, inserted_text.length() });
-            });
-
-            it("updates the parse tree", [&]() {
-                AssertThat(string(ts_document_string(doc)), Equals(
-                    "(object (string) (array (number) (number)) (string) (number))"));
-            });
-
-            it("re-reads only the changed portion of the input", [&]() {
-                AssertThat(reader->strings_read.size(), Equals<size_t>(2));
-                AssertThat(reader->strings_read[1], Equals(", \"key2\": 4 }"));
-            });
-        });
-
-        describe("modifying the beginning of the input", [&]() {
-            before_each([&]() {
-                size_t position(string("{ ").length());
-                string inserted_text("\"key2\": 4, ");
-
-                reader->content.insert(position, inserted_text);
-                ts_document_edit(doc, { position, 0, inserted_text.length() });
-            });
-
-            it("updates the parse tree", [&]() {
-                AssertThat(string(ts_document_string(doc)), Equals(
-                    "(object (string) (number) (string) (array (number) (number)))"));
-            });
-
-            it_skip("re-reads only the changed portion of the input", [&]() {
-                AssertThat(reader->strings_read.size(), Equals<size_t>(2));
-                AssertThat(reader->strings_read[1], Equals("\"key2\": 4, "));
-            });
-        });
+    it("parses the input", [&]() {
+      AssertThat(string(ts_document_string(doc)), Equals(
+          "(object (string) (array (number) (number)))"));
     });
 
+    it("reads the entire input", [&]() {
+      AssertThat(reader->strings_read, Equals(vector<string>({
+          "{ \"key\": [1, 2] }"
+      })));
+    });
+
+    describe("modifying the end of the input", [&]() {
+      before_each([&]() {
+        size_t position(string("{ \"key\": [1, 2]").length());
+        string inserted_text(", \"key2\": 4");
+
+        reader->content.insert(position, inserted_text);
+        ts_document_edit(doc, { position, 0, inserted_text.length() });
+      });
+
+      it("updates the parse tree", [&]() {
+        AssertThat(string(ts_document_string(doc)), Equals(
+            "(object (string) (array (number) (number)) (string) (number))"));
+      });
+
+      it("re-reads only the changed portion of the input", [&]() {
+        AssertThat(reader->strings_read.size(), Equals<size_t>(2));
+        AssertThat(reader->strings_read[1], Equals(", \"key2\": 4 }"));
+      });
+    });
+
+    describe("modifying the beginning of the input", [&]() {
+      before_each([&]() {
+        size_t position(string("{ ").length());
+        string inserted_text("\"key2\": 4, ");
+
+        reader->content.insert(position, inserted_text);
+        ts_document_edit(doc, { position, 0, inserted_text.length() });
+      });
+
+      it("updates the parse tree", [&]() {
+        AssertThat(string(ts_document_string(doc)), Equals(
+            "(object (string) (number) (string) (array (number) (number)))"));
+      });
+
+      it_skip("re-reads only the changed portion of the input", [&]() {
+        AssertThat(reader->strings_read.size(), Equals<size_t>(2));
+        AssertThat(reader->strings_read[1], Equals("\"key2\": 4, "));
+      });
+    });
+  });
 });
 
 END_TEST
diff --git a/src/runtime/document.c b/src/runtime/document.c
index 3bf7b5b0..a734998f 100644
--- a/src/runtime/document.c
+++ b/src/runtime/document.c
@@ -31,6 +31,8 @@ void ts_document_set_language(TSDocument *document,
                               const TSLanguage *language) {
   ts_parser_destroy(&document->parser);
   document->parser = ts_parser_make(language);
+  if (document->input.read_fn)
+    document->tree = ts_parser_parse(&document->parser, document->input, NULL);
 }
 
 const TSTree *ts_document_tree(const TSDocument *document) {
@@ -44,7 +46,8 @@ const char *ts_document_string(const TSDocument *document) {
 
 void ts_document_set_input(TSDocument *document, TSInput input) {
   document->input = input;
-  document->tree = ts_parser_parse(&document->parser, document->input, NULL);
+  if (document->parser.language)
+    document->tree = ts_parser_parse(&document->parser, document->input, NULL);
 }
 
 void ts_document_edit(TSDocument *document, TSInputEdit edit) {
@@ -96,8 +99,11 @@ void ts_document_set_input_string(TSDocument *document, const char *text) {
 }
 
 TSNode *ts_document_root_node(const TSDocument *document) {
-  return ts_node_make_root(document->tree,
-                           document->parser.language->symbol_names);
+  if (document->tree)
+    return ts_node_make_root(document->tree,
+                             document->parser.language->symbol_names);
+  else
+    return NULL;
 }
 
 TSNode *ts_document_get_node(const TSDocument *document, size_t pos) {