diff --git a/src/applications/conduit/parametertype/ConduitEpochParameterType.php b/src/applications/conduit/parametertype/ConduitEpochParameterType.php
--- a/src/applications/conduit/parametertype/ConduitEpochParameterType.php
+++ b/src/applications/conduit/parametertype/ConduitEpochParameterType.php
@@ -6,7 +6,15 @@
   protected function getParameterValue(array $request, $key) {
     $value = parent::getParameterValue($request, $key);
 
-    if (!is_int($value)) {
+    if (is_string($value) && ctype_digit($value)) {
+      $value = $value + 0;
+      if (!is_int($value)) {
+        $this->raiseValidationException(
+          $request,
+          $key,
+          pht('Epoch timestamp integer overflow.'));
+      }
+    } else if (!is_int($value)) {
       $this->raiseValidationException(
         $request,
         $key,