diff --git a/src/data-compat.c b/src/data-compat.c
index ec80172e..5c7d5431 100644
--- a/src/data-compat.c
+++ b/src/data-compat.c
@@ -187,7 +187,7 @@ old_user_read (gpgme_data_t dh, void *buffer, size_t size)
 				 buffer, size, &amt);
   if (err)
     return TRACE_SYSRES (gpgme_error_to_errno (err));
-  return TRACE_SYSRES (amt);
+  return TRACE_SYSRES ((gpgme_ssize_t)amt);
 }