diff --git a/src/file.h b/src/file.h
index dc49fe1e..f9181e94 100644
--- a/src/file.h
+++ b/src/file.h
@@ -122,10 +122,12 @@ public:
     // FIXME - these won't work when using the `--stdout' option
     virtual void seek(off_t off, int whence)
     {
+        assert(!opt->to_stdout);
         super::seek(off,whence);
     }
     virtual void rewrite(const void *buf, int len)
     {
+        assert(!opt->to_stdout);
         write(buf, len);
         bytes_written -= len;       // restore
     }
diff --git a/src/main.cpp b/src/main.cpp
index 5fbd2e74..e7a12594 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -229,6 +229,11 @@ void check_options(int i, int argc)
         opt->backup = 1;
 
     check_not_both(opt->to_stdout, opt->output_name != NULL, "--stdout", "-o");
+    if (opt->to_stdout && opt->cmd == CMD_COMPRESS)
+    {
+        fprintf(stderr,"%s: cannot use `--stdout' when compressing\n", argv0);
+        e_usage();
+    }
     if (opt->to_stdout || opt->output_name)
     {
         if (i + 1 != argc)