diff --git a/src/xdiff/xdiff.h b/src/xdiff/xdiff.h
index 3994f66..a9169d3 100644
--- a/src/xdiff/xdiff.h
+++ b/src/xdiff/xdiff.h
@@ -66,6 +66,7 @@
 
 /* merge output styles */
 #define XDL_MERGE_DIFF3 1
+#define XDL_MERGE_ZEALOUS_DIFF3 2
 
 typedef struct s_mmfile {
 	char *ptr;
@@ -126,6 +127,7 @@
 #endif
 
 #define xdl_malloc(x) lalloc((x), TRUE)
+#define xdl_calloc(n, sz) lalloc_clear(n*sz, TRUE)
 #define xdl_free(ptr) vim_free(ptr)
 #define xdl_realloc(ptr,x) vim_realloc((ptr),(x))