diff --git a/changelog.md b/changelog.md
index 8314c74..f9e9c8e 100644
--- a/changelog.md
+++ b/changelog.md
@@ -1,5 +1,9 @@
 # illogical changelog
 
+## 1.6.1
+
+- Bugfix on Arithmetic evaluate. Returns false when ContextValue is not present in the Context.
+
 ## 1.6.0
 
 - Added support for Arithmetic expressions within other Comparison expressions. This allows for
diff --git a/package-lock.json b/package-lock.json
index 8112d5c..3cf7942 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,12 +1,12 @@
 {
   "name": "@briza/illogical",
-  "version": "1.5.9",
+  "version": "1.6.1",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "@briza/illogical",
-      "version": "1.5.9",
+      "version": "1.6.1",
       "license": "MIT",
       "devDependencies": {
         "@babel/core": "^7.25.2",
diff --git a/package.json b/package.json
index 79c9777..555209b 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@briza/illogical",
-  "version": "1.6.0",
+  "version": "1.6.1",
   "description": "A micro conditional javascript engine used to parse the raw logical and comparison expressions, evaluate the expression in the given data context, and provide access to a text form of the given expressions.",
   "main": "lib/illogical.js",
   "module": "lib/illogical.esm.js",
diff --git a/types/expression/arithmetic/index.d.ts b/types/expression/arithmetic/index.d.ts
index 23c269c..a26a385 100644
--- a/types/expression/arithmetic/index.d.ts
+++ b/types/expression/arithmetic/index.d.ts
@@ -17,6 +17,16 @@ export declare abstract class Arithmetic implements Evaluable {
      * @param {Operand[]} operands Operands.
      */
     constructor(operator: string, operatorSymbol: symbol, operands: Operand[]);
+    /**
+     * Helper function to assist with arithmetic evaluation. Ensures that all
+     * operands are present and are numbers. Throws error if any operand is not a
+     * number.
+     *
+     * @param {Result[]} results
+     * @returns {number[] | false} false if any operand is missing, otherwise the
+     *   array of numbers
+     */
+    protected getResultValues(results: Result[]): number[] | false;
     /**
      * Performs the arithmetic operation on the operands evaluated values.
      * @param {Result[]} results Operand result values.