3 files changed, 4 insertions, 2 deletions

diff --git a/cache.h b/cache.h
index 139b911816..3c6b677418 100644
--- a/cache.h
+++ b/cache.h
@@ -345,6 +345,7 @@ static inline enum object_type object_type(unsigned int mode)
 #define GIT_DIR_ENVIRONMENT "GIT_DIR"
 #define GIT_NAMESPACE_ENVIRONMENT "GIT_NAMESPACE"
 #define GIT_WORK_TREE_ENVIRONMENT "GIT_WORK_TREE"
+#define GIT_PREFIX_ENVIRONMENT "GIT_PREFIX"
 #define DEFAULT_GIT_DIR_ENVIRONMENT ".git"
 #define DB_ENVIRONMENT "GIT_OBJECT_DIRECTORY"
 #define INDEX_ENVIRONMENT "GIT_INDEX_FILE"
diff --git a/environment.c b/environment.c
index 81ffb4b666..4fb7ceac3a 100644
--- a/environment.c
+++ b/environment.c
@@ -88,6 +88,7 @@ const char * const local_repo_env[] = {
 	GRAFT_ENVIRONMENT,
 	INDEX_ENVIRONMENT,
 	NO_REPLACE_OBJECTS_ENVIRONMENT,
+	GIT_PREFIX_ENVIRONMENT,
 	NULL
 };
 
diff --git a/setup.c b/setup.c
index 1b120175f2..d0e3ecdcd4 100644
--- a/setup.c
+++ b/setup.c
@@ -768,9 +768,9 @@ const char *setup_git_directory_gently(int *nongit_ok)
 
 	prefix = setup_git_directory_gently_1(nongit_ok);
 	if (prefix)
-		setenv("GIT_PREFIX", prefix, 1);
+		setenv(GIT_PREFIX_ENVIRONMENT, prefix, 1);
 	else
-		setenv("GIT_PREFIX", "", 1);
+		setenv(GIT_PREFIX_ENVIRONMENT, "", 1);
 
 	if (startup_info) {
 		startup_info->have_repository = !nongit_ok || !*nongit_ok;