diff --git a/src/panels/developer-tools/assist/developer-tools-assist.ts b/src/panels/developer-tools/assist/developer-tools-assist.ts
index 89e3890f5c..3e45b7e4dc 100644
--- a/src/panels/developer-tools/assist/developer-tools-assist.ts
+++ b/src/panels/developer-tools/assist/developer-tools-assist.ts
@@ -39,7 +39,7 @@ class HaPanelDevAssist extends SubscribeMixin(LitElement) {
     subscribe: false,
     storage: "localStorage",
   })
-  _language?: string;
+  _language = "en";
 
   @state() _results: SentenceParsingResult[] = [];
 
@@ -63,7 +63,7 @@ class HaPanelDevAssist extends SubscribeMixin(LitElement) {
     const sentences = this._sentencesInput.value
       .split("\n")
       .filter((a) => a !== "");
-    const { results } = await debugAgent(this.hass, sentences, this._language!);
+    const { results } = await debugAgent(this.hass, sentences, this._language);
 
     this._sentencesInput.value = "";
 
@@ -75,7 +75,7 @@ class HaPanelDevAssist extends SubscribeMixin(LitElement) {
 
       newResults.push({
         sentence,
-        language: this._language!,
+        language: this._language,
         result,
         time: now,
       });
@@ -111,7 +111,7 @@ class HaPanelDevAssist extends SubscribeMixin(LitElement) {
                   <ha-language-picker
                     .languages=${this.supportedLanguages}
                     .hass=${this.hass}
-                    .value=${this._language ?? "en"}
+                    .value=${this._language}
                     @value-changed=${this._languageChanged}
                   ></ha-language-picker>
                 `
@@ -124,10 +124,7 @@ class HaPanelDevAssist extends SubscribeMixin(LitElement) {
             ></ha-textarea>
           </div>
           <div class="card-actions">
-            <ha-button
-              @click=${this._parse}
-              .disabled=${!this._language || !this._validInput}
-            >
+            <ha-button @click=${this._parse} .disabled=${!this._validInput}>
               Parse sentences
             </ha-button>
           </div>