diff --git a/fs/expand_glob.ts b/fs/expand_glob.ts
index f32359c302b0..024ebb8eb42f 100644
--- a/fs/expand_glob.ts
+++ b/fs/expand_glob.ts
@@ -127,7 +127,7 @@ export async function* expandGlob(
   let fixedRoot = isGlobAbsolute
     ? winRoot !== undefined ? winRoot : "/"
     : absRoot;
-  while (segments.length > 0 && !isGlob(segments[0])) {
+  while (segments.length > 0 && !isGlob(segments[0]!)) {
     const seg = segments.shift();
     assert(seg !== undefined);
     fixedRoot = joinGlobs([fixedRoot, seg], globOptions);
@@ -253,7 +253,7 @@ export function* expandGlobSync(
   let fixedRoot = isGlobAbsolute
     ? winRoot !== undefined ? winRoot : "/"
     : absRoot;
-  while (segments.length > 0 && !isGlob(segments[0])) {
+  while (segments.length > 0 && !isGlob(segments[0]!)) {
     const seg = segments.shift();
     assert(seg !== undefined);
     fixedRoot = joinGlobs([fixedRoot, seg], globOptions);
diff --git a/fs/move_test.ts b/fs/move_test.ts
index 60dc4a15d7c8..3b2632d833c4 100644
--- a/fs/move_test.ts
+++ b/fs/move_test.ts
@@ -388,7 +388,7 @@ Deno.test("move() accepts overwrite option set to true for file content", async
     [file, url],
     [url, file],
     [url, url],
-  ];
+  ] as const;
 
   for (const p of pairs) {
     const src = p[0];
@@ -415,7 +415,7 @@ Deno.test("move() accepts overwrite option set to true for directories", async f
     [dir, url],
     [url, dir],
     [url, url],
-  ];
+  ] as const;
 
   for (const p of pairs) {
     const src = p[0];
@@ -446,7 +446,7 @@ Deno.test("moveSync() accepts overwrite option set to true for file content", fu
     [file, url],
     [url, file],
     [url, url],
-  ];
+  ] as const;
 
   for (const p of pairs) {
     const src = p[0];
@@ -473,7 +473,7 @@ Deno.test("move() accepts overwrite option set to true for directories", functio
     [dir, url],
     [url, dir],
     [url, url],
-  ];
+  ] as const;
 
   for (const p of pairs) {
     const src = p[0];
diff --git a/fs/testdata/empty_dir.ts b/fs/testdata/empty_dir.ts
index f8fcc1cebee6..105b536642d4 100644
--- a/fs/testdata/empty_dir.ts
+++ b/fs/testdata/empty_dir.ts
@@ -1,6 +1,6 @@
 import { emptyDir } from "../empty_dir.ts";
 
-emptyDir(Deno.args[0])
+emptyDir(Deno.args[0]!)
   .then(() => {
     Deno.stdout.write(new TextEncoder().encode("success"));
   })
diff --git a/fs/testdata/empty_dir_sync.ts b/fs/testdata/empty_dir_sync.ts
index c26092cc01ad..29a3b86d97a1 100644
--- a/fs/testdata/empty_dir_sync.ts
+++ b/fs/testdata/empty_dir_sync.ts
@@ -1,7 +1,7 @@
 import { emptyDirSync } from "../empty_dir.ts";
 
 try {
-  emptyDirSync(Deno.args[0]);
+  emptyDirSync(Deno.args[0]!);
   Deno.stdout.write(new TextEncoder().encode("success"));
 } catch (err) {
   Deno.stdout.write(