diff --git a/backend/api.js b/backend/api.js
index f0d78a4..af90c2c 100644
--- a/backend/api.js
+++ b/backend/api.js
@@ -304,7 +304,7 @@ export class Session {
         cmdline = `echo '${name} has no REPL, press Run to see it in action'`;
       }
       if (code === undefined) {
-        code = createEmpty !== undefined ? createEmpty : template;
+        code = createEmpty !== undefined ? createEmpty : template + "\n";
       }
       if (code && suffix) {
         code += suffix;
diff --git a/backend/langs.js b/backend/langs.js
index 510d42f..8e923e1 100644
--- a/backend/langs.js
+++ b/backend/langs.js
@@ -9,6 +9,22 @@ import { log } from "./util.js";
 // populated at runtime and updated asynchronously.
 export let langs = {};
 
+// Correct whitespace problems in a language configuration,
+// destructively. Return the fixed configuration.
+//
+// This basically removes leading and trailing whitespace from all
+// values in the configuration recursively.
+function fixupLangConfig(langConfig) {
+  if (typeof langConfig === "string") {
+    return langConfig.trim();
+  } else if (typeof langConfig === "object") {
+    for (const key in langConfig) {
+      langConfig[key] = fixupLangConfig(langConfig[key]);
+    }
+  }
+  return langConfig;
+}
+
 // Read languages from JSON files in /opt/riju/langs, and update the
 // global langs variable in this module. Never throw an error. If
 // there is a problem then just leave the languages as they previously
@@ -21,8 +37,8 @@ async function readLangsFromDisk() {
         continue;
       }
       const id = path.parse(filename).name;
-      const langConfig = JSON.parse(
-        await fs.readFile(`/opt/riju/langs/${filename}`, "utf-8")
+      const langConfig = fixupLangConfig(
+        JSON.parse(await fs.readFile(`/opt/riju/langs/${filename}`, "utf-8"))
       );
       if (langConfig.id !== id) {
         log.error(
diff --git a/backend/test-runner.js b/backend/test-runner.js
index 9e8882b..cd570a9 100644
--- a/backend/test-runner.js
+++ b/backend/test-runner.js
@@ -214,7 +214,7 @@ class Test {
   };
   testRun = async () => {
     const pattern = this.config.hello || "Hello, world!";
-    this.send({ event: "runCode", code: this.config.template });
+    this.send({ event: "runCode", code: this.config.template + "\n" });
     if (this.config.helloInput !== undefined) {
       sendInput(this.send, this.config.helloInput);
     }
@@ -229,7 +229,7 @@ class Test {
   testRunRepl = async () => {
     const input = this.config.runReplInput || this.config.input || "123 * 234";
     const output = this.config.runReplOutput || this.config.output || "28782";
-    this.send({ event: "runCode", code: this.config.template });
+    this.send({ event: "runCode", code: this.config.template + "\n" });
     sendInput(this.send, input);
     await this.waitForOutput(output);
   };
@@ -238,10 +238,7 @@ class Test {
     const after = this.config.scope.after;
     const input = this.config.scope.input || "x";
     const output = this.config.scope.output || "28782";
-    let allCode = this.config.template;
-    if (!allCode.endsWith("\n")) {
-      allCode += "\n";
-    }
+    let allCode = this.config.template + "\n";
     if (after) {
       allCode = allCode.replace(after + "\n", after + "\n" + code + "\n");
     } else {
@@ -253,7 +250,7 @@ class Test {
   };
   testFormat = async () => {
     const input = this.config.format.input;
-    const output = this.config.format.output || this.config.template;
+    const output = (this.config.format.output || this.config.template) + "\n";
     this.send({ event: "formatCode", code: input });
     const result = await this.wait("formatter response", (msg) => {
       if (msg.event === "formattedCode") {
@@ -265,16 +262,14 @@ class Test {
     }
   };
   testLsp = async () => {
+    const template = this.config.template + "\n";
     const insertedCode = this.config.lsp.code;
     const after = this.config.lsp.after;
     const item = this.config.lsp.item;
     const idx = after
-      ? this.config.template.indexOf(after) + after.length
-      : this.config.template.length;
-    const code =
-      this.config.template.slice(0, idx) +
-      insertedCode +
-      this.config.template.slice(idx);
+      ? template.indexOf(after) + after.length
+      : template.length;
+    const code = template.slice(0, idx) + insertedCode + template.slice(idx);
     const root = await this.wait("lspStarted message", (msg) => {
       if (msg.event === "lspStarted") {
         return msg.root;
@@ -538,7 +533,7 @@ class Test {
                 jsonrpc: "2.0",
                 id: msg.output.id,
                 result: Array(msg.output.params.items.length).fill(
-                  this.config.lsp.config == undefined
+                  this.config.lsp.config !== undefined
                     ? this.config.lsp.config
                     : {}
                 ),
@@ -560,11 +555,6 @@ class Test {
 
 function lint(lang) {
   const config = langs[lang];
-  if (!config.template.endsWith("\n")) {
-    throw new Error("template is missing a trailing newline");
-  }
-  // These can be removed when the types are adjusted to make these
-  // situations impossible.
   if (
     config.format &&
     !config.format.input &&
diff --git a/frontend/src/app.js b/frontend/src/app.js
index aa70f60..c899bb7 100644
--- a/frontend/src/app.js
+++ b/frontend/src/app.js
@@ -289,7 +289,7 @@ async function main() {
     scrollbar: { verticalScrollbarSize: 0 },
   });
   window.addEventListener("resize", () => editor.layout());
-  editor.getModel().setValue(config.template);
+  editor.getModel().setValue(config.template + "\n");
   monaco.editor.setModelLanguage(
     editor.getModel(),
     config.monacoLang || "plaintext"
diff --git a/langs/python.yaml b/langs/python.yaml
index 15e6f67..92784d3 100644
--- a/langs/python.yaml
+++ b/langs/python.yaml
@@ -20,7 +20,7 @@ install:
       chmod +x "${pkg}/opt/mspyls/Microsoft.Python.LanguageServer"
       ln -s "/opt/mspyls/Microsoft.Python.LanguageServer" "${pkg}/usr/local/bin/Microsoft.Python.LanguageServer"
 
-repl: >-
+repl: |
   python3 -u
 main: "main.py"
 template: |
@@ -31,7 +31,7 @@ scope:
     x = 123 * 234
 
 format:
-  run: >-
+  run: |
     black -
   input: |
     print('Hello, world!')
@@ -39,7 +39,7 @@ format:
 pkg:
   install: "pip3 install --user NAME"
   uninstall: "pip3 uninstall NAME"
-  search: >-
+  search: |
     python3 -c 'import json; from xmlrpc import client; print(json.dumps(client.ServerProxy("https://pypi.org/pypi").search({"name": "NAME"})))' | jq -r 'map(.name) | .[]'
 
 lsp:
diff --git a/tools/generate-build-script.js b/tools/generate-build-script.js
index e1cac0d..7d4479f 100644
--- a/tools/generate-build-script.js
+++ b/tools/generate-build-script.js
@@ -39,7 +39,7 @@ cat <<EOF > "\${pkg}/DEBIAN/control"
 ${debianControlData}
 EOF`);
   for (const part of manual || []) {
-    parts.push(part.trim());
+    parts.push(part);
   }
   return parts.join("\n\n");
 }