diff --git a/src/Table.php b/src/Table.php
index 1d4990e..b26a656 100644
--- a/src/Table.php
+++ b/src/Table.php
@@ -178,7 +178,10 @@ public function groupBy(string|int $field): Table
 
         foreach ($this->rows as $value) {
             $property = $value->get($field);
-            if (array_key_exists(strval($property), $result)) {
+            $property = $this->castVariableForStrval($property);
+            
+            if (!$property
+                || array_key_exists(strval($property), $result)) {
                 continue;
             }
             $result[$property] = $value;
@@ -187,6 +190,21 @@ public function groupBy(string|int $field): Table
         return self::make(array_values($result));
     }
 
+
+    /**
+     * strval sometimes crashes when passed a mixed value, this fixes that problem.
+     */
+    private function castVariableForStrval(mixed $property): bool|float|int|string|null
+    {
+        return match(gettype($property)) {
+            'boolean' => (bool) $property,
+            'double' => (float) $property,
+            'integer' => (int) $property,
+            'string' => (string) $property,
+            default => null,
+        };
+    }
+
     /**
      * Transform allows you to run a function over an entire table on a specific row
      */