diff --git a/.travis.yml b/.travis.yml
index f611cc3..7d53122 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,10 +1,9 @@
 language: go
 
 go:
-  - 1.7
-  - 1.8
-  - 1.9
-  - "1.10"
+  - "1.11"
+  - "1.12"
+  - "1.13"
   - tip
 
 script: make test-static
diff --git a/Makefile b/Makefile
index cf00cef..4dffce0 100644
--- a/Makefile
+++ b/Makefile
@@ -2,7 +2,7 @@ default: test
 
 test: build-libgit2
 	go run script/check-MakeGitError-thread-lock.go
-	go test ./...
+	go test --count=1 ./...
 
 install: build-libgit2
 	go install ./...
@@ -15,4 +15,4 @@ install-static: build-libgit2
 
 test-static: build-libgit2
 	go run script/check-MakeGitError-thread-lock.go
-	go test --tags "static" ./...
+	go test --count=1 --tags "static" ./...
diff --git a/credentials.go b/credentials.go
index 4e42b6e..038313b 100644
--- a/credentials.go
+++ b/credentials.go
@@ -2,6 +2,9 @@ package git
 
 /*
 #include <git2.h>
+#include <git2/sys/cred.h>
+
+git_credtype_t _go_git_cred_credtype(git_cred *cred);
 */
 import "C"
 import "unsafe"
@@ -27,7 +30,7 @@ func (o *Cred) HasUsername() bool {
 }
 
 func (o *Cred) Type() CredType {
-	return (CredType)(o.ptr.credtype)
+	return (CredType)(C._go_git_cred_credtype(o.ptr))
 }
 
 func credFromC(ptr *C.git_cred) *Cred {
diff --git a/go.mod b/go.mod
index 688b8e3..7a68658 100644
--- a/go.mod
+++ b/go.mod
@@ -1 +1,3 @@
 module github.com/libgit2/git2go
+
+go 1.13
diff --git a/merge.go b/merge.go
index bc672ce..955289a 100644
--- a/merge.go
+++ b/merge.go
@@ -132,7 +132,7 @@ func (mo *MergeOptions) toC() *C.git_merge_options {
 	}
 	return &C.git_merge_options{
 		version:          C.uint(mo.Version),
-		flags:            C.git_merge_flag_t(mo.TreeFlags),
+		flags:            C.uint32_t(mo.TreeFlags),
 		rename_threshold: C.uint(mo.RenameThreshold),
 		target_limit:     C.uint(mo.TargetLimit),
 		file_favor:       C.git_merge_file_favor_t(mo.FileFavor),
@@ -394,7 +394,7 @@ func populateCMergeFileOptions(c *C.git_merge_file_options, options MergeFileOpt
 	c.our_label = C.CString(options.OurLabel)
 	c.their_label = C.CString(options.TheirLabel)
 	c.favor = C.git_merge_file_favor_t(options.Favor)
-	c.flags = C.git_merge_file_flag_t(options.Flags)
+	c.flags = C.uint32_t(options.Flags)
 	c.marker_size = C.ushort(options.MarkerSize)
 }
 
diff --git a/odb.go b/odb.go
index fec0eb9..6489653 100644
--- a/odb.go
+++ b/odb.go
@@ -221,7 +221,7 @@ func (v *Odb) NewWriteStream(size int64, otype ObjectType) (*OdbWriteStream, err
 	runtime.LockOSThread()
 	defer runtime.UnlockOSThread()
 
-	ret := C.git_odb_open_wstream(&stream.ptr, v.ptr, C.git_off_t(size), C.git_object_t(otype))
+	ret := C.git_odb_open_wstream(&stream.ptr, v.ptr, C.git_object_size_t(size), C.git_object_t(otype))
 	runtime.KeepAlive(v)
 	if ret < 0 {
 		return nil, MakeGitError(ret)
diff --git a/stash.go b/stash.go
index 8743da8..6624bce 100644
--- a/stash.go
+++ b/stash.go
@@ -171,7 +171,7 @@ func (opts *StashApplyOptions) toC() (
 
 		optsC = &C.git_stash_apply_options{
 			version: C.GIT_STASH_APPLY_OPTIONS_VERSION,
-			flags:   C.git_stash_apply_flags(opts.Flags),
+			flags:   C.uint32_t(opts.Flags),
 		}
 		populateCheckoutOpts(&optsC.checkout_options, &opts.CheckoutOptions)
 		if opts.ProgressCallback != nil {
diff --git a/vendor/libgit2 b/vendor/libgit2
index 08cfa43..6777db8 160000
--- a/vendor/libgit2
+++ b/vendor/libgit2
@@ -1 +1 @@
-Subproject commit 08cfa43d0e1a9214a2f1239593686078e75e5636
+Subproject commit 6777db8e8343014d57c41b335e0c60af44d4e9f2
diff --git a/wrapper.c b/wrapper.c
index 11c2f32..3656773 100644
--- a/wrapper.c
+++ b/wrapper.c
@@ -2,6 +2,7 @@
 #include <git2.h>
 #include <git2/sys/odb_backend.h>
 #include <git2/sys/refdb_backend.h>
+#include <git2/sys/cred.h>
 
 typedef int (*gogit_submodule_cbk)(git_submodule *sm, const char *name, void *payload);
 
@@ -180,4 +181,8 @@ void _go_git_writestream_free(git_writestream *stream)
 	stream->free(stream);
 }
 
+git_credtype_t _go_git_cred_credtype(git_cred *cred) {
+	return cred->credtype;
+}
+
 /* EOF */