diff --git a/kagi-test.el b/kagi-test.el
index 57e6bcc..1435605 100644
--- a/kagi-test.el
+++ b/kagi-test.el
@@ -319,6 +319,17 @@ https://www.example.com"
         (setq kagi-summarizer-engine "steve")
         (expect (kagi-summarize dummy-https-url) :to-equal dummy-output)
         (let ((args (car (spy-calls-args-for #'kagi--call-summarizer 0))))
-          (expect (map-elt args "engine") :to-equal "cecil"))))))
+          (expect (map-elt args "engine") :to-equal "cecil")))
+      (it "returns a summary when the take-away style is requested"
+        (expect (kagi-summarize just-enough-text-input nil nil 'takeaway) :to-equal dummy-output))
+      (it "uses the summary style when an invalid format is given"
+        (kagi-summarize just-enough-text-input nil nil 'invalid)
+        (let ((args (car (spy-calls-args-for #'kagi--call-summarizer 0))))
+          (expect (map-elt args "summary_type") :to-equal 'summary)))
+      (it "uses the summary style when an invalid format is configured"
+        (setq kagi-summarizer-default-summary-format 'invalid)
+        (kagi-summarize just-enough-text-input)
+        (let ((args (car (spy-calls-args-for #'kagi--call-summarizer 0))))
+          (expect (map-elt args "summary_type") :to-equal 'summary))))))
 
 ;;; kagi-test.el ends here
diff --git a/kagi.el b/kagi.el
index cbb8359..8c1a686 100644
--- a/kagi.el
+++ b/kagi.el
@@ -551,6 +551,14 @@ to `kagi-summarizer-default-language'."
          (downcase kagi-summarizer-engine))
         (t "cecil")))
 
+(defun kagi--summarizer-format (hint)
+  "Return a valid summary type based on the type given in HINT."
+  (let ((choices '(summary takeaway)))
+    (cond ((seq-contains-p choices hint) hint)
+          ((seq-contains-p choices kagi-summarizer-default-summary-format)
+           kagi-summarizer-default-summary-format)
+          (t 'summary))))
+
 (defun kagi-summarize (text-or-url &optional language engine format)
   "Return the summary of the given TEXT-OR-URL.
 
@@ -567,7 +575,8 @@ of text and `takeaway' returns a bullet list."
           (kagi--summarizer-determine-language language))
          (kagi-summarizer-engine
           (kagi--summarizer-engine engine))
-         (kagi-summarizer-default-summary-format format))
+         (kagi-summarizer-default-summary-format
+          (kagi--summarizer-format format)))
     (if-let* ((response (if (kagi--url-p text-or-url)
                             (kagi--call-url-summarizer text-or-url)
                           (kagi--call-text-summarizer text-or-url)))