diff --git a/unix/uxpgnt.c b/unix/uxpgnt.c
index 8909ded6..707f9376 100644
--- a/unix/uxpgnt.c
+++ b/unix/uxpgnt.c
@@ -1191,6 +1191,7 @@ void run_agent(FILE *logfp, const char *symlink_path)
         exit(1);
     }
 
+    strbuf_free(upc->prompt_buf);
     conf_free(conf);
 }