diff --git a/docs/index_status.html b/docs/index_status.html
index 8e7bbbf..b5fdb93 100644
--- a/docs/index_status.html
+++ b/docs/index_status.html
@@ -696,6 +696,8 @@ <h2>9.3 Other arithmetic functors</h2>
                 <li>atan2/2.</li>
                 <li>tan/1.</li>
                 <li>pi/0.</li>
+                <li>e/0.</li>
+                <li>epsilon/0.</li>
             </ol>
         </div>
         <div class="indexed" id="bitwise-functors">
diff --git a/src/docs/content.index_status.template b/src/docs/content.index_status.template
index 17ed954..782cab1 100644
--- a/src/docs/content.index_status.template
+++ b/src/docs/content.index_status.template
@@ -335,6 +335,8 @@ The ProscriptLS aspiration includes implementing most of ISO Prolog and some add
                 <li>atan2/2.</li>
                 <li>tan/1.</li>
                 <li>pi/0.</li>
+                <li>e/0.</li>
+                <li>epsilon/0.</li>
             </ol>
         </div>
         <div class="indexed" id="bitwise-functors">
diff --git a/src/engine/foreign.js b/src/engine/foreign.js
index 5b206c2..671f305 100644
--- a/src/engine/foreign.js
+++ b/src/engine/foreign.js
@@ -42,6 +42,11 @@ function evaluate_expression(expression, evaluated)
         evaluated.value = Math.E;
         return true;
     }
+    else if (TAG(expression) === TAG_ATM && expression === lookup_atom("epsilon"))
+    {
+        evaluated.value = Number.EPSILON;
+        return true;
+    }
     else if (TAG(expression) === TAG_ATM && expression === lookup_atom("random_float"))
     {
         // returns a random value in the open interval 0.0 < Random < 1.0