diff --git a/CHANGELOG.md b/CHANGELOG.md
index ec5a0d336..9c50f1211 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -29,6 +29,11 @@ v0.23 + 1
 * Rebases can now be performed purely in-memory, without touching the
   repository's workdir.
 
+* When adding objects to the index, or when creating new tree or commit
+  objects, the inputs are validated to ensure that the dependent objects
+  exist and are of the correct type.  This object validation can be
+  disabled with the GIT_OPT_ENABLE_STRICT_OBJECT_CREATION option.
+
 ### API additions
 
 * `git_config_lock()` has been added, which allow for
diff --git a/src/object.c b/src/object.c
index e7c1fef09..ebf77fb47 100644
--- a/src/object.c
+++ b/src/object.c
@@ -14,7 +14,7 @@
 #include "blob.h"
 #include "tag.h"
 
-bool git_object__strict_input_validation = false;
+bool git_object__strict_input_validation = true;
 
 typedef struct {
 	const char	*str;	/* type name string */
diff --git a/tests/commit/write.c b/tests/commit/write.c
index 303d1ce58..96b7cc321 100644
--- a/tests/commit/write.c
+++ b/tests/commit/write.c
@@ -38,7 +38,7 @@ void test_commit_write__cleanup(void)
 
 	cl_git_sandbox_cleanup();
 
-	cl_git_pass(git_libgit2_opts(GIT_OPT_ENABLE_STRICT_OBJECT_CREATION, 0));
+	cl_git_pass(git_libgit2_opts(GIT_OPT_ENABLE_STRICT_OBJECT_CREATION, 1));
 }
 
 
@@ -196,10 +196,12 @@ static int create_commit_from_ids(
 	return ret;
 }
 
-void test_commit_write__doesnt_validate_objects_by_default(void)
+void test_commit_write__can_write_invalid_objects(void)
 {
 	git_oid expected_id, tree_id, parent_id, commit_id;
 
+	cl_git_pass(git_libgit2_opts(GIT_OPT_ENABLE_STRICT_OBJECT_CREATION, 0));
+
 	/* this is a valid tree and parent */
 	git_oid_fromstr(&tree_id, tree_id_str);
 	git_oid_fromstr(&parent_id, parent_id_str);
@@ -237,8 +239,6 @@ void test_commit_write__can_validate_objects(void)
 {
 	git_oid tree_id, parent_id, commit_id;
 
-	cl_git_pass(git_libgit2_opts(GIT_OPT_ENABLE_STRICT_OBJECT_CREATION, 1));
-
 	/* this is a valid tree and parent */
 	git_oid_fromstr(&tree_id, tree_id_str);
 	git_oid_fromstr(&parent_id, parent_id_str);
diff --git a/tests/index/add.c b/tests/index/add.c
index cfa81c4d9..f101ea266 100644
--- a/tests/index/add.c
+++ b/tests/index/add.c
@@ -20,7 +20,7 @@ void test_index_add__cleanup(void)
 	cl_git_sandbox_cleanup();
 	g_repo = NULL;
 
-	cl_git_pass(git_libgit2_opts(GIT_OPT_ENABLE_STRICT_OBJECT_CREATION, 0));
+	cl_git_pass(git_libgit2_opts(GIT_OPT_ENABLE_STRICT_OBJECT_CREATION, 1));
 }
 
 static void test_add_entry(
@@ -42,7 +42,7 @@ static void test_add_entry(
 void test_index_add__invalid_entries_succeeds_by_default(void)
 {
 	/*
-	 * Ensure that there is no validation on ids by default
+	 * Ensure that there is validation on object ids by default
 	 */
 
 	/* ensure that we can add some actually good entries */
@@ -50,27 +50,6 @@ void test_index_add__invalid_entries_succeeds_by_default(void)
 	test_add_entry(true, valid_blob_id, GIT_FILEMODE_BLOB_EXECUTABLE);
 	test_add_entry(true, valid_blob_id, GIT_FILEMODE_LINK);
 
-	/* test that we fail to add some invalid (missing) blobs and trees */
-	test_add_entry(true, invalid_id, GIT_FILEMODE_BLOB);
-	test_add_entry(true, invalid_id, GIT_FILEMODE_BLOB_EXECUTABLE);
-	test_add_entry(true, invalid_id, GIT_FILEMODE_LINK);
-
-	/* test that we validate the types of objects */
-	test_add_entry(true, valid_commit_id, GIT_FILEMODE_BLOB);
-	test_add_entry(true, valid_tree_id, GIT_FILEMODE_BLOB_EXECUTABLE);
-	test_add_entry(true, valid_commit_id, GIT_FILEMODE_LINK);
-
-	/*
-	 * Ensure that strict object references will fail the `index_add`
-	 */
-
-	cl_git_pass(git_libgit2_opts(GIT_OPT_ENABLE_STRICT_OBJECT_CREATION, 1));
-
-	/* ensure that we can add some actually good entries */
-	test_add_entry(true, valid_blob_id, GIT_FILEMODE_BLOB);
-	test_add_entry(true, valid_blob_id, GIT_FILEMODE_BLOB_EXECUTABLE);
-	test_add_entry(true, valid_blob_id, GIT_FILEMODE_LINK);
-
 	/* test that we fail to add some invalid (missing) blobs and trees */
 	test_add_entry(false, invalid_id, GIT_FILEMODE_BLOB);
 	test_add_entry(false, invalid_id, GIT_FILEMODE_BLOB_EXECUTABLE);
@@ -80,5 +59,26 @@ void test_index_add__invalid_entries_succeeds_by_default(void)
 	test_add_entry(false, valid_commit_id, GIT_FILEMODE_BLOB);
 	test_add_entry(false, valid_tree_id, GIT_FILEMODE_BLOB_EXECUTABLE);
 	test_add_entry(false, valid_commit_id, GIT_FILEMODE_LINK);
+
+	/*
+	 * Ensure that there we can disable validation
+	 */
+
+	cl_git_pass(git_libgit2_opts(GIT_OPT_ENABLE_STRICT_OBJECT_CREATION, 0));
+
+	/* ensure that we can add some actually good entries */
+	test_add_entry(true, valid_blob_id, GIT_FILEMODE_BLOB);
+	test_add_entry(true, valid_blob_id, GIT_FILEMODE_BLOB_EXECUTABLE);
+	test_add_entry(true, valid_blob_id, GIT_FILEMODE_LINK);
+
+	/* test that we can now add some invalid (missing) blobs and trees */
+	test_add_entry(true, invalid_id, GIT_FILEMODE_BLOB);
+	test_add_entry(true, invalid_id, GIT_FILEMODE_BLOB_EXECUTABLE);
+	test_add_entry(true, invalid_id, GIT_FILEMODE_LINK);
+
+	/* test that we do not validate the types of objects */
+	test_add_entry(true, valid_commit_id, GIT_FILEMODE_BLOB);
+	test_add_entry(true, valid_tree_id, GIT_FILEMODE_BLOB_EXECUTABLE);
+	test_add_entry(true, valid_commit_id, GIT_FILEMODE_LINK);
 }
 
diff --git a/tests/object/tree/write.c b/tests/object/tree/write.c
index f779b8ce6..341f5db72 100644
--- a/tests/object/tree/write.c
+++ b/tests/object/tree/write.c
@@ -19,7 +19,7 @@ void test_object_tree_write__cleanup(void)
 {
    cl_git_sandbox_cleanup();
 
-	cl_git_pass(git_libgit2_opts(GIT_OPT_ENABLE_STRICT_OBJECT_CREATION, 0));
+	cl_git_pass(git_libgit2_opts(GIT_OPT_ENABLE_STRICT_OBJECT_CREATION, 1));
 }
 
 void test_object_tree_write__from_memory(void)
@@ -492,11 +492,11 @@ static void test_invalid_objects(bool should_allow_invalid)
 
 void test_object_tree_write__object_validity(void)
 {
-	/* Ensure that we can add invalid objects by default */
-	test_invalid_objects(true);
-
-	/* Ensure that we can turn on validation */
-	cl_git_pass(git_libgit2_opts(GIT_OPT_ENABLE_STRICT_OBJECT_CREATION, 1));
+	/* Ensure that we cannot add invalid objects by default */
 	test_invalid_objects(false);
+
+	/* Ensure that we can turn off validation */
+	cl_git_pass(git_libgit2_opts(GIT_OPT_ENABLE_STRICT_OBJECT_CREATION, 0));
+	test_invalid_objects(true);
 }