diff --git a/postler/postler-content.vala b/postler/postler-content.vala
index 7cf230e..940e44a 100644
--- a/postler/postler-content.vala
+++ b/postler/postler-content.vala
@@ -442,7 +442,7 @@ public class Postler.Content : WebKit.WebView {
         TimeVal time = new TimeVal ();
         int offset = 0;
         if (parsed != null) {
-            parsed.to_timeval (time);
+            Soup.date_to_timeval (parsed, time);
             offset = parsed.offset;
         }
         return new DateTime.from_timeval_local (time).add_minutes (offset);
diff --git a/postler/postler.vapi b/postler/postler.vapi
index 929932e..5626409 100644
--- a/postler/postler.vapi
+++ b/postler/postler.vapi
@@ -28,3 +28,8 @@ namespace Gdk {
                                             out Gdk.Rectangle dest);
     }
 
+[CCode (cprefix = "Soup", lower_case_cprefix = "soup_")]
+namespace Soup {
+    [CCode (cname = "soup_date_to_timeval", cheader_filename = "libsoup/soup.h")]
+    public void date_to_timeval (Soup.Date date, GLib.TimeVal time);
+}