diff --git a/keyboard.c b/keyboard.c
index 3eb086a..6135adb 100644
--- a/keyboard.c
+++ b/keyboard.c
@@ -515,9 +515,10 @@ create_and_upload_keymap(struct kbd *kb, const char *name, uint32_t comp_unichr,
 		exit(9);
 	}
 	const char *keymap_template = keymaps[keymap_index];
-	const size_t keymap_size = strlen(keymap_template) + 64;
+	size_t keymap_size = strlen(keymap_template) + 64;
 	char *keymap_str = malloc(keymap_size);
 	sprintf(keymap_str, keymap_template, comp_unichr, comp_shift_unichr);
+	keymap_size = strlen(keymap_str);
 	int keymap_fd = os_create_anonymous_file(keymap_size);
 	if (keymap_fd < 0) {
 		die("could not create keymap fd\n");