diff --git a/fsck-cache.c b/fsck-cache.c
index ca24a1b844..e53d01a40f 100644
--- a/fsck-cache.c
+++ b/fsck-cache.c
@@ -454,7 +454,7 @@ int main(int argc, char **argv)
 	if (standalone && check_full)
 		die("Only one of --standalone or --full can be used.");
 	if (standalone)
-		unsetenv("GIT_ALTERNATE_OBJECT_DIRECTORIES");
+		putenv("GIT_ALTERNATE_OBJECT_DIRECTORIES=");
 
 	fsck_head_link();
 	fsck_object_dir(get_object_directory());
diff --git a/receive-pack.c b/receive-pack.c
index 3a1b2ab694..1ef0c13935 100644
--- a/receive-pack.c
+++ b/receive-pack.c
@@ -269,7 +269,7 @@ int main(int argc, char **argv)
 
 	/* If we have a ".git" directory, chdir to it */
 	chdir(".git");
-	setenv("GIT_DIR", ".", 1);
+	putenv("GIT_DIR=.");
 
 	if (access("objects", X_OK) < 0 || access("refs/heads", X_OK) < 0)
 		die("%s doesn't appear to be a git directory", dir);
diff --git a/upload-pack.c b/upload-pack.c
index 95d3812051..da10742c44 100644
--- a/upload-pack.c
+++ b/upload-pack.c
@@ -179,7 +179,7 @@ int main(int argc, char **argv)
 	chdir(".git");
 	if (access("objects", X_OK) || access("refs", X_OK))
 		die("git-upload-pack: %s doesn't seem to be a git archive", dir);
-	setenv("GIT_DIR", ".", 1);
+	putenv("GIT_DIR=.");
 	upload_pack();
 	return 0;
 }