diff --git a/CHANGES b/CHANGES
index fd6f2a2d364855017b6d32fb5288ad7375982ab3..a4ae465508f3c000fb96bb84690fbe04ed0c0967 100644
--- a/CHANGES
+++ b/CHANGES
@@ -5,6 +5,12 @@
 
  Changes between 0.9.3a and 0.9.4
 
+  *) When bntest is run from "make test" it drives bc to check its
+     calculations, as well as internally checking them. If an internal check
+     fails, it needs to cause bc to give a non-zero result or make test carries
+     on without noticing the failure. Fixed.
+     [Ben Laurie]
+
   *) DES library cleanups.
      [Ulf Möller]
 
diff --git a/crypto/bn/bntest.c b/crypto/bn/bntest.c
index d0e9be6cda7eeeb035c683c7f611c7d95baf95df..c9bd0b877314ecaaa6731bb99c3b5ecb9bdc544f 100644
--- a/crypto/bn/bntest.c
+++ b/crypto/bn/bntest.c
@@ -212,6 +212,7 @@ int main(int argc, char *argv[])
 /**/
 	exit(0);
 err:
+	BIO_puts(out,"1\n"); /* make sure bc fails if we are piping to it */
 	ERR_load_crypto_strings();
 	ERR_print_errors(out);
 	exit(1);