diff --git a/include/git2/merge.h b/include/git2/merge.h
index 8a1dfec2e..610b0d509 100644
--- a/include/git2/merge.h
+++ b/include/git2/merge.h
@@ -85,7 +85,7 @@ typedef struct {
 } git_merge_opts;
 
 #define GIT_MERGE_OPTS_VERSION 1
-#define GIT_MERGE_OPTS_INIT {GIT_MERGE_OPTS_VERSION, 0, GIT_MERGE_TREE_OPTS_INIT, GIT_CHECKOUT_OPTS_INIT}
+#define GIT_MERGE_OPTS_INIT {GIT_MERGE_OPTS_VERSION, (git_merge_flags_t)0, GIT_MERGE_TREE_OPTS_INIT, GIT_CHECKOUT_OPTS_INIT}
 
 
 /**