diff --git a/arch/arm/mach-pxa/viper.c b/arch/arm/mach-pxa/viper.c
index 130379fb9d0f..ac733e91f3e4 100644
--- a/arch/arm/mach-pxa/viper.c
+++ b/arch/arm/mach-pxa/viper.c
@@ -768,8 +768,7 @@ static unsigned long viper_tpm;
 
 static int __init viper_tpm_setup(char *str)
 {
-	strict_strtoul(str, 10, &viper_tpm);
-	return 1;
+	return strict_strtoul(str, 10, &viper_tpm) >= 0;
 }
 
 __setup("tpm=", viper_tpm_setup);