diff --git a/src/ValueObjects/ToolCall.php b/src/ValueObjects/ToolCall.php
index 7329979ed..2da29fa39 100644
--- a/src/ValueObjects/ToolCall.php
+++ b/src/ValueObjects/ToolCall.php
@@ -34,10 +34,13 @@ public function arguments(): array
                 return [];
             }
 
-            $arguments = $this->arguments;
+            // Sanitize control characters that some providers (e.g. DeepSeek) may include
+            // in streamed tool call arguments. Raw 0x00-0x1F / 0x7F bytes are never valid
+            // in JSON (RFC 8259) and cause json_decode to throw "Control character error".
+            $arguments = preg_replace('/[\x00-\x1F\x7F]/', '', $this->arguments);
 
             return json_decode(
-                $arguments,
+                (string) $arguments,
                 true,
                 flags: JSON_THROW_ON_ERROR
             );