diff --git a/src/pygit2.c b/src/pygit2.c
index 0ab9c120b..b478e4b30 100644
--- a/src/pygit2.c
+++ b/src/pygit2.c
@@ -602,6 +602,9 @@ PyInit__pygit2(void)
     ADD_CONSTANT_INT(m, GIT_MERGE_ANALYSIS_UP_TO_DATE)
     ADD_CONSTANT_INT(m, GIT_MERGE_ANALYSIS_FASTFORWARD)
     ADD_CONSTANT_INT(m, GIT_MERGE_ANALYSIS_UNBORN)
+    ADD_CONSTANT_INT(m, GIT_MERGE_PREFERENCE_NONE)
+    ADD_CONSTANT_INT(m, GIT_MERGE_PREFERENCE_NO_FASTFORWARD)
+    ADD_CONSTANT_INT(m, GIT_MERGE_PREFERENCE_FASTFORWARD_ONLY)
 
     /* Describe */
     ADD_CONSTANT_INT(m, GIT_DESCRIBE_DEFAULT);