diff --git a/script/gallery.ts b/script/gallery.ts
index fb0ea66..43fe933 100644
--- a/script/gallery.ts
+++ b/script/gallery.ts
@@ -174,7 +174,7 @@ function sortFiltersUses(e: Event) {
 
 
 function setup() {
-  function inputs(id: string) {
+  function inputs(id: string): Boxes {
     let iter = document.getElementById(id)!.getElementsByTagName('input');
     return new Set(Array.from(iter));
   }
diff --git a/script/single.ts b/script/single.ts
index 0623093..87195ae 100644
--- a/script/single.ts
+++ b/script/single.ts
@@ -4,7 +4,7 @@ let mainlink: HTMLAnchorElement;
 let altButtons: HTMLInputElement[];
 let skipAll: HTMLInputElement;
 
-let opened = new Set;
+let opened: Set<string> = new Set;
 
 function openCW(id: string | null, caption: HTMLElement | null,
                 focusLink = false) {
@@ -51,8 +51,7 @@ function setImage(id: string | null,
   mainlink.href = href;
 }
 
-function activateButton(button: HTMLInputElement,
-                        doPush = true) {
+function activateButton(button: HTMLInputElement, doPush = true): void {
   setImage(button.id, button.value,
            button.dataset.link!,
            button.dataset.warning!);
@@ -60,7 +59,7 @@ function activateButton(button: HTMLInputElement,
   if (doPush) history.pushState(null, '', '#' + button.id);
 }
 
-function useFragment(firstLoad = false) {
+function useFragment(firstLoad = false): void {
   let button = altButtons[0];
 
   let frag = decodeURIComponent(location.hash).replace(/^#/, '');