diff --git a/ext/intl/spoofchecker/spoofchecker_main.c b/ext/intl/spoofchecker/spoofchecker_main.c
index 35f7aef810223..a890f468e130f 100644
--- a/ext/intl/spoofchecker/spoofchecker_main.c
+++ b/ext/intl/spoofchecker/spoofchecker_main.c
@@ -43,7 +43,8 @@ PHP_METHOD(Spoofchecker, isSuspicious)
 
 	if (error_code) {
 		zval_ptr_dtor(error_code);
-		ZVAL_LONG(error_code, ret);
+		ZVAL_LONG(Z_REFVAL_P(error_code), ret);
+		Z_TRY_ADDREF_P(error_code);
 	}
 	RETVAL_BOOL(ret != 0);
 }
@@ -76,7 +77,8 @@ PHP_METHOD(Spoofchecker, areConfusable)
 
 	if (error_code) {
 		zval_ptr_dtor(error_code);
-		ZVAL_LONG(error_code, ret);
+		ZVAL_LONG(Z_REFVAL_P(error_code), ret);
+		Z_TRY_ADDREF_P(error_code);
 	}
 	RETVAL_BOOL(ret != 0);
 }
diff --git a/ext/intl/tests/gh10647.phpt b/ext/intl/tests/gh10647.phpt
new file mode 100644
index 0000000000000..61c6b87e0ddec
--- /dev/null
+++ b/ext/intl/tests/gh10647.phpt
@@ -0,0 +1,24 @@
+--TEST--
+Bug GH-10647 (Spoofchecker::isSuspicious $errorCode always null)
+--SKIPIF--
+<?php
+if (!extension_loaded("intl")) die("skip intl extension not available");
+?>
+--FILE--
+<?php
+$error = 123;
+var_dump($error);
+
+$x = new Spoofchecker();
+var_dump($x->isSuspicious("\u{041F}aypal.com", $error));
+var_dump($error);
+
+var_dump($x->areConfusable('google.com', 'goog1e.com', $error));
+var_dump($error);
+?>
+--EXPECTF--
+int(123)
+bool(true)
+int(%d)
+bool(true)
+int(%d)