diff --git a/common/rdr/FileInStream.cxx b/common/rdr/FileInStream.cxx
index 18a9169..6d23aa2 100644
--- a/common/rdr/FileInStream.cxx
+++ b/common/rdr/FileInStream.cxx
@@ -72,7 +72,7 @@
     size_t n = fread((U8 *)end, b + sizeof(b) - end, 1, file);
     if (n < 1) {
       if (n < 0 || ferror(file))
-        throw Exception(strerror(errno));
+        throw SystemException("fread", errno);
       if (feof(file))
         throw EndOfStream();
       if (n == 0) { return 0; }