diff --git a/Zend/zend.c b/Zend/zend.c
index 4f40ebc4f95a..2e37bdb28527 100644
--- a/Zend/zend.c
+++ b/Zend/zend.c
@@ -223,7 +223,7 @@ static ZEND_INI_MH(OnUpdateReservedStackSize) /* {{{ */
 static ZEND_INI_MH(OnUpdateFiberStackSize) /* {{{ */
 {
 	if (new_value) {
-		EG(fiber_stack_size) = zend_ini_parse_quantity_warn(new_value, entry->name);
+		EG(fiber_stack_size) = zend_ini_parse_uquantity_warn(new_value, entry->name);
 	} else {
 		EG(fiber_stack_size) = ZEND_FIBER_DEFAULT_C_STACK_SIZE;
 	}
diff --git a/Zend/zend_globals.h b/Zend/zend_globals.h
index 9c109e967cd5..a2439b80eabc 100644
--- a/Zend/zend_globals.h
+++ b/Zend/zend_globals.h
@@ -269,7 +269,7 @@ struct _zend_executor_globals {
 	zend_fiber *active_fiber;
 
 	/* Default fiber C stack size. */
-	zend_long fiber_stack_size;
+	size_t fiber_stack_size;
 
 	/* If record_errors is enabled, all emitted diagnostics will be recorded,
 	 * in addition to being processed as usual. */