diff --git a/net/wireless/Makefile b/net/wireless/Makefile
index 8158b375d170..4500ad5f2a61 100644
--- a/net/wireless/Makefile
+++ b/net/wireless/Makefile
@@ -27,7 +27,7 @@ $(obj)/shipped-certs.c: $(wildcard $(srctree)/$(src)/certs/*.hex)
 	@$(kecho) "  GEN     $@"
 	@(echo '#include "reg.h"'; \
 	  echo 'const u8 shipped_regdb_certs[] = {'; \
-	  cat $^ ; \
+	  echo | cat - $^ ; \
 	  echo '};'; \
 	  echo 'unsigned int shipped_regdb_certs_len = sizeof(shipped_regdb_certs);'; \
 	 ) > $@