diff --git a/src/battery-type.js b/src/battery-type.js
index f3f8564..3bdf139 100644
--- a/src/battery-type.js
+++ b/src/battery-type.js
@@ -1,3 +1,5 @@
+'use strict'
+
 module.exports = letter => {
   switch (letter) {
     case 'F':
diff --git a/src/body-type.js b/src/body-type.js
index 44563b6..38b49ef 100644
--- a/src/body-type.js
+++ b/src/body-type.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const S = (letter, year) => {
   switch (year) {
     case 2012:
diff --git a/src/index.js b/src/index.js
index 83e7f0d..681594d 100644
--- a/src/index.js
+++ b/src/index.js
@@ -1,7 +1,5 @@
 'use strict'
 
-// TODO: add vin locations photos
-
 const debug = require('debug-logfmt')('tesla-vin')
 
 const digit = (input, start, end) => (end ? input.slice(start - 1, end) : input[start - 1])
diff --git a/src/model.js b/src/model.js
index 5781e19..6b5086c 100644
--- a/src/model.js
+++ b/src/model.js
@@ -1,3 +1,5 @@
+'use strict'
+
 module.exports = input => {
   switch (input) {
     case 'S':
diff --git a/src/motor.js b/src/motor.js
index d93d621..cf7643b 100644
--- a/src/motor.js
+++ b/src/motor.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const S = (letter, year) => {
   switch (year) {
     case 2012:
diff --git a/src/photos.js b/src/photos.js
index 63e3354..2eb2cb2 100644
--- a/src/photos.js
+++ b/src/photos.js
@@ -1,4 +1,6 @@
-const PREFIX = 'https://teslahunt.github.io/vin/images'
+'use strict'
+
+const BASE_URL = 'https://teslahunt.github.io/vin/images'
 
 const S = year => {
   switch (year) {
@@ -6,20 +8,20 @@ const S = year => {
     case 2013:
     case 2014:
     case 2015:
-      return [`${PREFIX}/S/1.jpeg`, `${PREFIX}/S/2.jpeg`, `${PREFIX}/S/3.jpeg`]
+      return [`${BASE_URL}/S/1.jpeg`, `${BASE_URL}/S/2.jpeg`, `${BASE_URL}/S/3.jpeg`]
     case 2016:
     case 2017:
     case 2018:
     case 2019:
     case 2020:
       return [
-        `${PREFIX}/S/1.jpeg`,
-        `${PREFIX}/S/2.jpeg`,
-        `${PREFIX}/S/3.jpeg`,
-        `${PREFIX}/S/4.jpeg`
+        `${BASE_URL}/S/1.jpeg`,
+        `${BASE_URL}/S/2.jpeg`,
+        `${BASE_URL}/S/3.jpeg`,
+        `${BASE_URL}/S/4.jpeg`
       ]
     default:
-      return [`${PREFIX}/S/5.jpeg`, `${PREFIX}/S/6.jpeg`, `${PREFIX}/S/7.jpeg`]
+      return [`${BASE_URL}/S/5.jpeg`, `${BASE_URL}/S/6.jpeg`, `${BASE_URL}/S/7.jpeg`]
   }
 }
 
@@ -31,29 +33,29 @@ const X = year => {
     case 2018:
     case 2019:
     case 2020:
-      return [`${PREFIX}/X/1.jpeg`, `${PREFIX}/X/2.jpeg`, `${PREFIX}/X/3.jpeg`]
+      return [`${BASE_URL}/X/1.jpeg`, `${BASE_URL}/X/2.jpeg`, `${BASE_URL}/X/3.jpeg`]
     default:
-      return [`${PREFIX}/X/4.jpeg`, `${PREFIX}/X/5.jpeg`, `${PREFIX}/X/6.jpeg`]
+      return [`${BASE_URL}/X/4.jpeg`, `${BASE_URL}/X/5.jpeg`, `${BASE_URL}/X/6.jpeg`]
   }
 }
 
 const Y = () => {
   return [
-    `${PREFIX}/Y/1.jpeg`,
-    `${PREFIX}/Y/2.jpeg`,
-    `${PREFIX}/Y/3.jpeg`,
-    `${PREFIX}/Y/4.jpeg`,
-    `${PREFIX}/Y/5.jpeg`
+    `${BASE_URL}/Y/1.jpeg`,
+    `${BASE_URL}/Y/2.jpeg`,
+    `${BASE_URL}/Y/3.jpeg`,
+    `${BASE_URL}/Y/4.jpeg`,
+    `${BASE_URL}/Y/5.jpeg`
   ]
 }
 
 const _3 = () => {
   return [
-    `${PREFIX}/3/1.jpeg`,
-    `${PREFIX}/3/2.jpeg`,
-    `${PREFIX}/3/3.jpeg`,
-    `${PREFIX}/3/4.jpeg`,
-    `${PREFIX}/3/5.jpeg`
+    `${BASE_URL}/3/1.jpeg`,
+    `${BASE_URL}/3/2.jpeg`,
+    `${BASE_URL}/3/3.jpeg`,
+    `${BASE_URL}/3/4.jpeg`,
+    `${BASE_URL}/3/5.jpeg`
   ]
 }
 
diff --git a/src/plan-of-manufacture.js b/src/plan-of-manufacture.js
index 44caf5d..af8b7c5 100644
--- a/src/plan-of-manufacture.js
+++ b/src/plan-of-manufacture.js
@@ -1,3 +1,5 @@
+'use strict'
+
 module.exports = letter => {
   switch (letter) {
     case 'A':
diff --git a/src/restraint-systems.js b/src/restraint-systems.js
index 8b7deb0..5fbbc95 100644
--- a/src/restraint-systems.js
+++ b/src/restraint-systems.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const X = (letter, year) => {
   switch (year) {
     case 2016:
diff --git a/src/world-manufacturing-identifier.js b/src/world-manufacturing-identifier.js
index 4f99ffe..bae997b 100644
--- a/src/world-manufacturing-identifier.js
+++ b/src/world-manufacturing-identifier.js
@@ -1,3 +1,5 @@
+'use strict'
+
 module.exports = letter => {
   switch (letter) {
     case '5YJ':
diff --git a/src/year.js b/src/year.js
index dcc8f62..07ed96c 100644
--- a/src/year.js
+++ b/src/year.js
@@ -1,3 +1,5 @@
+'use strict'
+
 module.exports = letter => {
   switch (letter) {
     case 'C':