diff --git a/builder/xenserver/common/config/common_config.go b/builder/xenserver/common/config/common_config.go
index 0cd041b..beca954 100644
--- a/builder/xenserver/common/config/common_config.go
+++ b/builder/xenserver/common/config/common_config.go
@@ -171,8 +171,9 @@ func (c *CommonConfig) Prepare(upper interface{}, raws ...interface{}) ([]string
 
 	// Validation
 
-	if c.HTTPPortMin > c.HTTPPortMax {
-		errs = packersdk.MultiErrorAppend(errs, errors.New("the HTTP min port must be less than the max"))
+	// Lower bound is not checked in commonsteps.HTTPConfig
+	if c.HTTPPortMin < 0 {
+		errs = packersdk.MultiErrorAppend(errs, errors.New("the HTTP min port must greater than zero"))
 	}
 
 	switch c.Format {
diff --git a/builder/xenserver/iso/config.go b/builder/xenserver/iso/config.go
index 1f28e0b..fd41e7a 100644
--- a/builder/xenserver/iso/config.go
+++ b/builder/xenserver/iso/config.go
@@ -70,7 +70,7 @@ type Config struct {
 func (c *Config) Prepare(raws ...interface{}) ([]string, []string, error) {
 	var errs *packersdk.MultiError
 
-	params, warnings, merrs := c.CommonConfig.Prepare(c, raws)
+	params, warnings, merrs := c.CommonConfig.Prepare(c, raws...)
 	if merrs != nil {
 		errs = packersdk.MultiErrorAppend(errs, merrs)
 	}
diff --git a/builder/xenserver/xva/config.go b/builder/xenserver/xva/config.go
index 21d2239..71459ef 100644
--- a/builder/xenserver/xva/config.go
+++ b/builder/xenserver/xva/config.go
@@ -17,7 +17,7 @@ type Config struct {
 
 func (c *Config) Prepare(raws ...interface{}) ([]string, []string, error) {
 	var errs *packersdk.MultiError
-	params, warnings, merrs := c.CommonConfig.Prepare(c, raws)
+	params, warnings, merrs := c.CommonConfig.Prepare(c, raws...)
 	if merrs != nil {
 		errs = packersdk.MultiErrorAppend(errs, merrs)
 	}