diff --git a/.travis.yml b/.travis.yml
index 2ae08be..b5c249e 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -19,10 +19,11 @@ go:
   - 1.9.x
   - 1.10.x
   - 1.11.x
+  - master
 
 before_install:
   - |
-    if [[ "$TRAVIS_OS_NAME" == "osx" ]]; then 
+    if [[ "$TRAVIS_OS_NAME" == "osx" ]]; then
       brew update
     fi
   - |
diff --git a/callback.go b/callback.go
index 2c68973..e8c492b 100644
--- a/callback.go
+++ b/callback.go
@@ -368,7 +368,7 @@ func callbackRet(typ reflect.Type) (callbackRetConverter, error) {
 func callbackError(ctx *C.sqlite3_context, err error) {
 	cstr := C.CString(err.Error())
 	defer C.free(unsafe.Pointer(cstr))
-	C.sqlite3_result_error(ctx, cstr, -1)
+	C.sqlite3_result_error(ctx, cstr, C.int(-1))
 }
 
 // Test support code. Tests are not allowed to import "C", so we can't
diff --git a/sqlite3.go b/sqlite3.go
index 942b0b5..d75e8b0 100644
--- a/sqlite3.go
+++ b/sqlite3.go
@@ -1674,7 +1674,7 @@ func (c *SQLiteConn) prepare(ctx context.Context, query string) (driver.Stmt, er
 	defer C.free(unsafe.Pointer(pquery))
 	var s *C.sqlite3_stmt
 	var tail *C.char
-	rv := C._sqlite3_prepare_v2_internal(c.db, pquery, -1, &s, &tail)
+	rv := C._sqlite3_prepare_v2_internal(c.db, pquery, C.int(-1), &s, &tail)
 	if rv != C.SQLITE_OK {
 		return nil, c.lastError()
 	}
@@ -1718,7 +1718,7 @@ func (c *SQLiteConn) GetFilename(schemaName string) string {
 // GetLimit returns the current value of a run-time limit.
 // See: sqlite3_limit, http://www.sqlite.org/c3ref/limit.html
 func (c *SQLiteConn) GetLimit(id int) int {
-	return int(C._sqlite3_limit(c.db, C.int(id), -1))
+	return int(C._sqlite3_limit(c.db, C.int(id), C.int(-1)))
 }
 
 // SetLimit changes the value of a run-time limits.