diff -r 1d2be1b31e70 -r d7c4ba50b7d8 dav/sync.c
--- a/dav/sync.c	Mon Nov 14 19:02:40 2016 +0100
+++ b/dav/sync.c	Fri Nov 18 13:39:20 2016 +0100
@@ -55,7 +55,10 @@
 static DavContext *ctx;
 
 static void xmlerrorfnc(void * c, const char * msg, ... ) {
-    // nothing
+    va_list ap;
+    va_start(ap, msg);
+    vfprintf(stderr, msg, ap);
+    va_end(ap);
 }
 
 int main(int argc, char **argv) {