diff --git a/lib/plugins/definitions.js b/lib/plugins/definitions.js
index 09ac7b8c..20a22e04 100644
--- a/lib/plugins/definitions.js
+++ b/lib/plugins/definitions.js
@@ -38,7 +38,7 @@ module.exports = {
     },
     output: {
       validator: output => !output || RELEASE_TYPE.includes(output),
-      message: 'The "analyzeCommits" plugin output must be either undefined or a valid semver release type.',
+      message: 'The "analyzeCommits" plugin output, if defined, must be a valid semver release type.',
     },
   },
   verifyRelease: {
diff --git a/lib/plugins/normalize.js b/lib/plugins/normalize.js
index 3a6175fb..4b508a9e 100644
--- a/lib/plugins/normalize.js
+++ b/lib/plugins/normalize.js
@@ -27,7 +27,7 @@ module.exports = (pluginType, pluginConfig, logger, validator) => {
     const result = await func(cloneDeep(input));
 
     if (validator && !validator.validator(result)) {
-      throw new Error(`${validator.message}. Received: ${inspect(result)}`);
+      throw new Error(`${validator.message} Received: ${inspect(result)}`);
     }
     return result;
   };
diff --git a/test/plugins/normalize.test.js b/test/plugins/normalize.test.js
index 7667e03d..d0957752 100644
--- a/test/plugins/normalize.test.js
+++ b/test/plugins/normalize.test.js
@@ -40,7 +40,7 @@ test('Wrap plugin in a function that validate the output of the plugin', async t
   const pluginFunction = stub().resolves(1);
   const plugin = normalize('', pluginFunction, t.context.logger, {
     validator: output => output === 1,
-    message: 'The output must be 1',
+    message: 'The output must be 1.',
   });
 
   await t.notThrows(plugin());