diff --git a/fast-import.c b/fast-import.c
index 55ffae4fa6..bea12151c2 100644
--- a/fast-import.c
+++ b/fast-import.c
@@ -630,7 +630,7 @@ static void start_packfile(void)
 	int pack_fd;
 
 	snprintf(tmpfile, sizeof(tmpfile),
-		"%s/pack_XXXXXX", get_object_directory());
+		"%s/tmp_pack_XXXXXX", get_object_directory());
 	pack_fd = mkstemp(tmpfile);
 	if (pack_fd < 0)
 		die("Can't create %s: %s", tmpfile, strerror(errno));
@@ -730,7 +730,7 @@ static char *create_index(void)
 	}
 
 	snprintf(tmpfile, sizeof(tmpfile),
-		"%s/index_XXXXXX", get_object_directory());
+		"%s/tmp_idx_XXXXXX", get_object_directory());
 	idx_fd = mkstemp(tmpfile);
 	if (idx_fd < 0)
 		die("Can't create %s: %s", tmpfile, strerror(errno));
diff --git a/index-pack.c b/index-pack.c
index 61eb20e45b..6284fe3760 100644
--- a/index-pack.c
+++ b/index-pack.c
@@ -139,7 +139,7 @@ static const char *open_pack_file(const char *pack_name)
 		if (!pack_name) {
 			static char tmpfile[PATH_MAX];
 			snprintf(tmpfile, sizeof(tmpfile),
-				 "%s/pack_XXXXXX", get_object_directory());
+				 "%s/tmp_pack_XXXXXX", get_object_directory());
 			output_fd = mkstemp(tmpfile);
 			pack_name = xstrdup(tmpfile);
 		} else
@@ -690,7 +690,7 @@ static const char *write_index_file(const char *index_name, unsigned char *sha1)
 	if (!index_name) {
 		static char tmpfile[PATH_MAX];
 		snprintf(tmpfile, sizeof(tmpfile),
-			 "%s/index_XXXXXX", get_object_directory());
+			 "%s/tmp_idx_XXXXXX", get_object_directory());
 		fd = mkstemp(tmpfile);
 		index_name = xstrdup(tmpfile);
 	} else {
diff --git a/sha1_file.c b/sha1_file.c
index 940bab5612..e412c70f27 100644
--- a/sha1_file.c
+++ b/sha1_file.c
@@ -1979,7 +1979,7 @@ int write_sha1_file(void *buf, unsigned long len, const char *type, unsigned cha
 		return error("sha1 file %s: %s\n", filename, strerror(errno));
 	}
 
-	snprintf(tmpfile, sizeof(tmpfile), "%s/obj_XXXXXX", get_object_directory());
+	snprintf(tmpfile, sizeof(tmpfile), "%s/tmp_obj_XXXXXX", get_object_directory());
 
 	fd = mkstemp(tmpfile);
 	if (fd < 0) {
@@ -2105,7 +2105,7 @@ int write_sha1_from_fd(const unsigned char *sha1, int fd, char *buffer,
 	int ret;
 	SHA_CTX c;
 
-	snprintf(tmpfile, sizeof(tmpfile), "%s/obj_XXXXXX", get_object_directory());
+	snprintf(tmpfile, sizeof(tmpfile), "%s/tmp_obj_XXXXXX", get_object_directory());
 
 	local = mkstemp(tmpfile);
 	if (local < 0) {