diff --git a/rules/utils.go b/rules/utils.go
index d6ba470..9ab6741 100644
--- a/rules/utils.go
+++ b/rules/utils.go
@@ -50,18 +50,21 @@ var validMachineTypes = map[string]bool{
 	"c3-standard-88-lssd":   true,
 	"c3-standard-176":       true,
 	"c3-standard-176-lssd":  true,
+	"c3-standard-192-metal": true,
 	"c3-highmem-4":          true,
 	"c3-highmem-8":          true,
 	"c3-highmem-22":         true,
 	"c3-highmem-44":         true,
 	"c3-highmem-88":         true,
 	"c3-highmem-176":        true,
+	"c3-highmem-192-metal":  true,
 	"c3-highcpu-4":          true,
 	"c3-highcpu-8":          true,
 	"c3-highcpu-22":         true,
 	"c3-highcpu-44":         true,
 	"c3-highcpu-88":         true,
 	"c3-highcpu-176":        true,
+	"c3-highcpu-192-metal":  true,
 	"c3d-standard-4":        true,
 	"c3d-standard-8":        true,
 	"c3d-standard-8-lssd":   true,
@@ -100,6 +103,31 @@ var validMachineTypes = map[string]bool{
 	"c3d-highcpu-90":        true,
 	"c3d-highcpu-180":       true,
 	"c3d-highcpu-360":       true,
+	// C4
+	"c4-standard-2":   true,
+	"c4-standard-4":   true,
+	"c4-standard-8":   true,
+	"c4-standard-16":  true,
+	"c4-standard-32":  true,
+	"c4-standard-48":  true,
+	"c4-standard-96":  true,
+	"c4-standard-192": true,
+	"c4-highcpu-2":    true,
+	"c4-highcpu-4":    true,
+	"c4-highcpu-8":    true,
+	"c4-highcpu-16":   true,
+	"c4-highcpu-32":   true,
+	"c4-highcpu-48":   true,
+	"c4-highcpu-96":   true,
+	"c4-highcpu-192":  true,
+	"c4-highmem-2":    true,
+	"c4-highmem-4":    true,
+	"c4-highmem-8":    true,
+	"c4-highmem-16":   true,
+	"c4-highmem-32":   true,
+	"c4-highmem-48":   true,
+	"c4-highmem-96":   true,
+	"c4-highmem-192":  true,
 	// E2
 	"e2-micro":       true,
 	"e2-small":       true,
@@ -309,6 +337,11 @@ var validMachineTypes = map[string]bool{
 	// Z3
 	"z3-highmem-88":  true,
 	"z3-highmem-176": true,
+
+	// X4 machine types: https://cloud.google.com/compute/docs/memory-optimized-machines#x4_machine_types
+	"x4-megamem-960-metal":  true,
+	"x4-megamem-1440-metal": true,
+	"x4-megamem-1920-metal": true,
 }
 
 func isCustomType(machineType string) bool {