diff --git a/git-compat-util.h b/git-compat-util.h
index 400e921..dc1948a 100644
--- a/git-compat-util.h
+++ b/git-compat-util.h
@@ -623,6 +623,7 @@
 extern void *xrealloc(void *ptr, size_t size);
 extern void *xcalloc(size_t nmemb, size_t size);
 extern void *xmmap(void *start, size_t length, int prot, int flags, int fd, off_t offset);
+extern void *xmmap_gently(void *start, size_t length, int prot, int flags, int fd, off_t offset);
 extern ssize_t xread(int fd, void *buf, size_t len);
 extern ssize_t xwrite(int fd, const void *buf, size_t len);
 extern ssize_t xpread(int fd, void *buf, size_t len, off_t offset);