Index: src/core/loader.cpp
===================================================================
--- src/core/loader.cpp
+++ src/core/loader.cpp
@@ -52,7 +52,9 @@
 
     QStringList languagesNameCache;
     QHash<QString, QSharedPointer<SpellerPlugin> > spellerCache;
+    static bool defaultPluginIgnored;
 };
+bool LoaderPrivate::defaultPluginIgnored = false;
 
 Q_GLOBAL_STATIC(Loader, s_loader)
 
@@ -107,7 +109,9 @@
             bool unknown = !std::any_of(lClients.constBegin(), lClients.constEnd(), [backend] (const Client *client) {
                     return client->name() == backend; });
             if (unknown) {
-                qCWarning(SONNET_LOG_CORE) << "Default client" << backend << "doesn't support language:" << plang;
+                if (!d->defaultPluginIgnored) {
+                    qCWarning(SONNET_LOG_CORE) << "Default client" << backend << "doesn't support language:" << plang;
+                }
                 backend = QString();
             }
         }
@@ -329,6 +333,28 @@
         plugin.unload(); // don't leave it in memory
         return;
     }
+    const auto backend = d->settings->defaultClient();
+    QList< QPair<const char*,QString> > forceUseMap = {
+        {"SONNET_USE_ASPELL", QStringLiteral("ASpell")}
+        , {"SONNET_USE_ENCHANT", QStringLiteral("Enchant")}
+        , {"SONNET_USE_HSPELL", QStringLiteral("HSpell")}
+        , {"SONNET_USE_HUNSPELL", QStringLiteral("Hunspell")}
+#ifdef Q_OS_MACOS
+        , {"SONNET_USE_NSSPELLCHECKER", QStringLiteral("NSSpellChecker")}
+#endif
+    };
+    for (const auto &forceUse : forceUseMap) {
+        if (qEnvironmentVariableIsSet(forceUse.first)) {
+            if (client->name() != forceUse.second) {
+                qCWarning(SONNET_LOG_CORE) << "Ignoring" << client->name();
+                if (client->name() == backend) {
+                    d->defaultPluginIgnored = true;
+                }
+                plugin.unload();
+                return;
+            }
+        }
+    }
 #else
     Client *client = nullptr;
     if (pluginPath == QLatin1String("Hunspell")) {