diff --git a/src/modules/module-protocol-pulse/modules/module-switch-on-connect.c b/src/modules/module-protocol-pulse/modules/module-switch-on-connect.c
index 33150d517..0af92c53a 100644
--- a/src/modules/module-protocol-pulse/modules/module-switch-on-connect.c
+++ b/src/modules/module-protocol-pulse/modules/module-switch-on-connect.c
@@ -271,6 +271,9 @@ static int module_switch_on_connect_prepare(struct module * const module)
 	if ((str = pw_properties_get(props, "blocklist")) == NULL)
 		str = DEFAULT_BLOCKLIST;
 
+	if (strlen(str) > 1024)
+		return -EINVAL;
+
 	if (regcomp(&d->blocklist, str, REG_NOSUB | REG_EXTENDED) != 0)
 		return -EINVAL;