diff --git a/archive-tar.c b/archive-tar.c
index 6eaf59eb01..63cc2eca11 100644
--- a/archive-tar.c
+++ b/archive-tar.c
@@ -268,19 +268,17 @@ static int write_tar_entry(const unsigned char *sha1, const char *base,
 
 int write_tar_archive(struct archiver_args *args)
 {
-	int plen = args->base ? strlen(args->base) : 0;
-
 	git_config(git_tar_config, NULL);
 
 	archive_time = args->time;
 	verbose = args->verbose;
 	commit = args->commit;
-	base_len = args->base ? strlen(args->base) : 0;
+	base_len = args->baselen;
 
 	if (args->commit_sha1)
 		write_global_extended_header(args->commit_sha1);
 
-	if (args->base && plen > 0 && args->base[plen - 1] == '/') {
+	if (args->baselen > 0 && args->base[args->baselen - 1] == '/') {
 		char *base = xstrdup(args->base);
 		int baselen = strlen(base);
 
@@ -290,7 +288,7 @@ int write_tar_archive(struct archiver_args *args)
 				0, NULL);
 		free(base);
 	}
-	read_tree_recursive(args->tree, args->base, plen, 0,
+	read_tree_recursive(args->tree, args->base, args->baselen, 0,
 			    args->pathspec, write_tar_entry, NULL);
 	write_trailer();
 
diff --git a/archive-zip.c b/archive-zip.c
index 0d24f3fe37..d18254c5c0 100644
--- a/archive-zip.c
+++ b/archive-zip.c
@@ -316,17 +316,15 @@ static void dos_time(time_t *time, int *dos_date, int *dos_time)
 
 int write_zip_archive(struct archiver_args *args)
 {
-	int plen = strlen(args->base);
-
 	dos_time(&args->time, &zip_date, &zip_time);
 
 	zip_dir = xmalloc(ZIP_DIRECTORY_MIN_SIZE);
 	zip_dir_size = ZIP_DIRECTORY_MIN_SIZE;
 	verbose = args->verbose;
 	commit = args->commit;
-	base_len = args->base ? strlen(args->base) : 0;
+	base_len = args->baselen;
 
-	if (args->base && plen > 0 && args->base[plen - 1] == '/') {
+	if (args->baselen > 0 && args->base[args->baselen - 1] == '/') {
 		char *base = xstrdup(args->base);
 		int baselen = strlen(base);
 
@@ -336,7 +334,7 @@ int write_zip_archive(struct archiver_args *args)
 				0, NULL);
 		free(base);
 	}
-	read_tree_recursive(args->tree, args->base, plen, 0,
+	read_tree_recursive(args->tree, args->base, args->baselen, 0,
 			    args->pathspec, write_zip_entry, NULL);
 	write_zip_trailer(args->commit_sha1);
 
diff --git a/archive.h b/archive.h
index 1b24ae310d..34151f41b4 100644
--- a/archive.h
+++ b/archive.h
@@ -6,6 +6,7 @@
 
 struct archiver_args {
 	const char *base;
+	size_t baselen;
 	struct tree *tree;
 	const unsigned char *commit_sha1;
 	const struct commit *commit;
diff --git a/builtin-archive.c b/builtin-archive.c
index 6ee36775e7..e7f4ec6341 100644
--- a/builtin-archive.c
+++ b/builtin-archive.c
@@ -192,6 +192,7 @@ int parse_archive_args(int argc, const char **argv, const struct archiver **ar,
 	}
 	args->verbose = verbose;
 	args->base = base;
+	args->baselen = strlen(base);
 
 	return i;
 }