diff --git a/desktop/src/preload.js b/desktop/src/preload.js
--- a/desktop/src/preload.js
+++ b/desktop/src/preload.js
@@ -25,7 +25,11 @@
       ipcRenderer.removeListener('on-new-version-available', withEvent);
   },
   updateToNewVersion: () => ipcRenderer.send('update-to-new-version'),
-  platform: { win32: 'windows', darwin: 'macos' }[process.platform],
+  platform: (
+    { win32: 'windows', darwin: 'macos' } as Partial<
+      Record<typeof process.platform, 'windows' | 'macos'>,
+    >
+  )[process.platform],
   onDeviceTokenRegistered: callback => {
     const withEvent = (event: IpcRendererEvent, ...args: $ReadOnlyArray<any>) =>
       callback(...args);
diff --git a/lib/flow-typed/environments/node.js b/lib/flow-typed/environments/node.js
--- a/lib/flow-typed/environments/node.js
+++ b/lib/flow-typed/environments/node.js
@@ -3394,7 +3394,18 @@
   };
   nextTick: <T>(cb: (...T) => mixed, ...T) => void;
   pid : number;
-  platform : string;
+  platform : 
+    | "aix"
+    | "android"
+    | "darwin"
+    | "freebsd"
+    | "haiku"
+    | "linux"
+    | "openbsd"
+    | "sunos"
+    | "win32"
+    | "cygwin"
+    | "netbsd";
   release : {
     name : string,
     lts? : string,