diff --git a/src/dc_tools.rs b/src/dc_tools.rs
index fdaca5262..b11c3b9a7 100644
--- a/src/dc_tools.rs
+++ b/src/dc_tools.rs
@@ -1561,6 +1561,11 @@ pub fn to_string(s: *const libc::c_char) -> String {
     let cstr = unsafe { CStr::from_ptr(s) };
 
     cstr.to_str().map(|s| s.to_string()).unwrap_or_else(|err| {
+        eprintln!(
+            "Non utf8 string: '{:?}' ({:?})",
+            cstr.to_string_lossy(),
+            err
+        );
         panic!("Non utf8 string: '{:?}' ({:?})", cstr.to_bytes(), err);
     })
 }