diff --git a/runtime/src/server/middleware/index.ts b/runtime/src/server/middleware/index.ts
index 96fd9ea05..823b1aaa8 100644
--- a/runtime/src/server/middleware/index.ts
+++ b/runtime/src/server/middleware/index.ts
@@ -121,8 +121,14 @@ export function serve({ prefix, pathname, cache_control }: {
 				res.setHeader('Cache-Control', cache_control);
 				res.end(data);
 			} catch (err) {
-				res.statusCode = 404;
-				res.end('not found');
+				// [#1442](https://github.com/sveltejs/sapper/issues/1142)
+				// Requests to addresses under "/client" cannot be filtered out on their prefix, and can therefore end up here.
+				if (req.path.startsWith(prefix) && !/\..*$/.test(req.path)) {
+					next();
+				} else {
+					res.statusCode = 404;
+					res.end('not found');
+				}
 			}
 		} else {
 			next();
diff --git a/test/apps/basics/src/routes/apple/new.svelte b/test/apps/basics/src/routes/apple/new.svelte
new file mode 100644
index 000000000..a9d787cc5
--- /dev/null
+++ b/test/apps/basics/src/routes/apple/new.svelte
@@ -0,0 +1 @@
+Success.
diff --git a/test/apps/basics/src/routes/client/client/new.svelte b/test/apps/basics/src/routes/client/client/new.svelte
new file mode 100644
index 000000000..ef8e05020
--- /dev/null
+++ b/test/apps/basics/src/routes/client/client/new.svelte
@@ -0,0 +1 @@
+<h1>Success.</h1>
diff --git a/test/apps/basics/src/routes/client/index.svelte b/test/apps/basics/src/routes/client/index.svelte
new file mode 100644
index 000000000..ef8e05020
--- /dev/null
+++ b/test/apps/basics/src/routes/client/index.svelte
@@ -0,0 +1 @@
+<h1>Success.</h1>
diff --git a/test/apps/basics/src/routes/client/new.svelte b/test/apps/basics/src/routes/client/new.svelte
new file mode 100644
index 000000000..ef8e05020
--- /dev/null
+++ b/test/apps/basics/src/routes/client/new.svelte
@@ -0,0 +1 @@
+<h1>Success.</h1>
diff --git a/test/apps/basics/test.ts b/test/apps/basics/test.ts
index f1313b81a..9467bfb95 100644
--- a/test/apps/basics/test.ts
+++ b/test/apps/basics/test.ts
@@ -383,6 +383,15 @@ describe('basics', function() {
 		assert.equal(await r.text('h2'), 'Called 1 time');
 	});
 
+	it('finds routes under /client/', async () => {
+		await r.load('/client');
+		assert.equal(await r.text('h1'), 'Success.');
+		await r.load('/client/new');
+		assert.equal(await r.text('h1'), 'Success.');
+		await r.load('/client/client/new');
+		assert.equal(await r.text('h1'), 'Success.');
+	});
+
 	it('survives the tests with no server errors', () => {
 		assert.deepEqual(r.errors, []);
 	});