diff --git a/keyserver/src/creators/day-creator.js b/keyserver/src/creators/day-creator.js
--- a/keyserver/src/creators/day-creator.js
+++ b/keyserver/src/creators/day-creator.js
@@ -5,6 +5,8 @@
 import { dbQuery, SQL } from '../database/database';
 import createIDs from './id-creator';
 
+const MYSQL_DUPLICATE_ENTRY_FOR_KEY_ERROR_CODE = 1062;
+
 async function fetchOrCreateDayID(
   threadID: string,
   date: string,
@@ -30,7 +32,7 @@
     await dbQuery(insertQuery);
     return id;
   } catch (e) {
-    if (e.errno !== 1062) {
+    if (e.errno !== MYSQL_DUPLICATE_ENTRY_FOR_KEY_ERROR_CODE) {
       throw new ServerError('unknown_error');
     }
     // There's a race condition that can happen if two people start editing
diff --git a/keyserver/src/database/database.js b/keyserver/src/database/database.js
--- a/keyserver/src/database/database.js
+++ b/keyserver/src/database/database.js
@@ -84,6 +84,8 @@
 FakeSQLResult.prototype = Array.prototype;
 const fakeResult: QueryResults = (new FakeSQLResult(): any);
 
+const MYSQL_DEADLOCK_ERROR_CODE = 1213;
+
 type QueryOptions = {
   +triesLeft?: number,
   +multipleStatements?: boolean,
@@ -122,7 +124,7 @@
     }
     return await connection.query(statement);
   } catch (e) {
-    if (e.errno === 1213 && triesLeft > 0) {
+    if (e.errno === MYSQL_DEADLOCK_ERROR_CODE && triesLeft > 0) {
       console.log('deadlock occurred, trying again', e);
       return await dbQuery(statement, { ...options, triesLeft: triesLeft - 1 });
     }
diff --git a/keyserver/src/database/migrations.js b/keyserver/src/database/migrations.js
--- a/keyserver/src/database/migrations.js
+++ b/keyserver/src/database/migrations.js
@@ -42,11 +42,13 @@
   return true;
 }
 
+const MYSQL_TABLE_DOESNT_EXIST_ERROR_CODE = 1146;
+
 async function setUpDBAndReturnVersion(): Promise<number> {
   try {
     return await fetchDBVersion();
   } catch (e) {
-    if (e.errno !== 1146) {
+    if (e.errno !== MYSQL_TABLE_DOESNT_EXIST_ERROR_CODE) {
       throw e;
     }
     await setupDB();