diff --git a/README.org b/README.org
index 07c8915..d6f69db 100644
--- a/README.org
+++ b/README.org
@@ -268,6 +268,10 @@ The full changelog can be found in README.org.
 
 - Show a welcome message when starting the FastGPT shell (=kagi-fastgpt-shell=). This can be customized with =kagi-fastgpt-welcome-function=, a variable with a function that returns a welcome string.
 
+*** Fixes
+
+- Prompts defined with =define-kagi-fastgpt-prompt= wouldn't always work when expanding =%s= placeholders (possibly resulting in =Lisp error: (args-out-of-range 0 7)=).
+
 *** Misc
 
 - Minor refactoring in the code calling the FastGPT API.
diff --git a/kagi.el b/kagi.el
index 0e98f4a..e39d96f 100644
--- a/kagi.el
+++ b/kagi.el
@@ -465,7 +465,9 @@ user input."
                               (lambda (match)
                                 (pcase match
                                   ("%%" "%")
-                                  ("%s" (or user-text (setq user-text (funcall text-function))))
+                                  ("%s" (or user-text
+                                            (setq user-text (save-match-data
+                                                              (funcall text-function)))))
                                   (_ match)))
                               prompt t t)))
 
diff --git a/kagi.info b/kagi.info
index 7f9725f..08e0d2a 100644
Binary files a/kagi.info and b/kagi.info differ