diff --git a/crypto/opensslconf.h.in b/crypto/opensslconf.h.in
index 504d93d0a..4429c911a 100644
--- a/crypto/opensslconf.h.in
+++ b/crypto/opensslconf.h.in
@@ -118,7 +118,7 @@
 #endif
 
 #if defined(DES_RISC1) && defined(DES_RISC2)
-YOU SHOULD NOT HAVE BOTH DES_RISC1 AND DES_RISC2 DEFINED!!!!!
+#error YOU SHOULD NOT HAVE BOTH DES_RISC1 AND DES_RISC2 DEFINED!!!!!
 #endif
 
 /* Unroll the inner loop, this sometimes helps, sometimes hinders.