diff --git a/src/core/Ingredient.mjs b/src/core/Ingredient.mjs
index 5902e2da..1c0f0cc3 100644
--- a/src/core/Ingredient.mjs
+++ b/src/core/Ingredient.mjs
@@ -145,7 +145,7 @@ class Ingredient {
                 const valStr = (checkVal !== null && checkVal !== undefined) ? String(checkVal).toLowerCase() : "";
                 const matchedOption = permittedOptions.find(opt => opt.toLowerCase() === valStr);
                 if (!matchedOption) {
-                    throw new OperationError(`${this.name} must be one of the following: ${permittedOptions.join(", ")}`);
+                    throw new OperationError(`${this.name} must be one of the following: ${permittedOptions.join(", ")}.`);
                 }
             }
         }
diff --git a/tests/operations/tests/AutomatedValidation.mjs b/tests/operations/tests/AutomatedValidation.mjs
index e9d16029..f55efa01 100644
--- a/tests/operations/tests/AutomatedValidation.mjs
+++ b/tests/operations/tests/AutomatedValidation.mjs
@@ -121,7 +121,7 @@ TestRegister.addTests([
     {
         name: "Automated Validation: Invalid Option value",
         input: "test",
-        expectedOutput: "Option Ingredient must be one of the following: Option 1, Option 2, Option 3",
+        expectedOutput: "Option Ingredient must be one of the following: Option 1, Option 2, Option 3.",
         recipeConfig: [
             {
                 op: "Automated Validation Test Op",
@@ -132,7 +132,7 @@ TestRegister.addTests([
     {
         name: "Automated Validation: Option value as optgroup heading (invalid)",
         input: "test",
-        expectedOutput: "Option Ingredient must be one of the following: Option 1, Option 2, Option 3",
+        expectedOutput: "Option Ingredient must be one of the following: Option 1, Option 2, Option 3.",
         recipeConfig: [
             {
                 op: "Automated Validation Test Op",
diff --git a/tests/operations/tests/GenerateLoremIpsum.mjs b/tests/operations/tests/GenerateLoremIpsum.mjs
index 145f2884..6861752c 100644
--- a/tests/operations/tests/GenerateLoremIpsum.mjs
+++ b/tests/operations/tests/GenerateLoremIpsum.mjs
@@ -67,7 +67,7 @@ TestRegister.addTests([
     {
         name: "Generate Lorem Ipsum: Incorrect lengthType",
         input: "",
-        expectedOutput: "Length in must be one of the following: Paragraphs, Sentences, Words, Bytes",
+        expectedOutput: "Length in must be one of the following: Paragraphs, Sentences, Words, Bytes.",
         recipeConfig: [
             {
                 "op": "Generate Lorem Ipsum",