diff --git a/google/resource_compute_router_nat.go b/google/resource_compute_router_nat.go
index fa8c82a4306..22956cbb7ff 100644
--- a/google/resource_compute_router_nat.go
+++ b/google/resource_compute_router_nat.go
@@ -721,41 +721,29 @@ func flattenComputeRouterNatMinPortsPerVm(v interface{}, d *schema.ResourceData)
 }
 
 func flattenComputeRouterNatUdpIdleTimeoutSec(v interface{}, d *schema.ResourceData) interface{} {
-	// Handles the string fixed64 format
-	if strVal, ok := v.(string); ok {
-		if intVal, err := strconv.ParseInt(strVal, 10, 64); err == nil {
-			return intVal
-		} // let terraform core handle it if we can't convert the string to an int.
+	if v == nil || v.(string) == "" {
+		return 30
 	}
 	return v
 }
 
 func flattenComputeRouterNatIcmpIdleTimeoutSec(v interface{}, d *schema.ResourceData) interface{} {
-	// Handles the string fixed64 format
-	if strVal, ok := v.(string); ok {
-		if intVal, err := strconv.ParseInt(strVal, 10, 64); err == nil {
-			return intVal
-		} // let terraform core handle it if we can't convert the string to an int.
+	if v == nil || v.(string) == "" {
+		return 30
 	}
 	return v
 }
 
 func flattenComputeRouterNatTcpEstablishedIdleTimeoutSec(v interface{}, d *schema.ResourceData) interface{} {
-	// Handles the string fixed64 format
-	if strVal, ok := v.(string); ok {
-		if intVal, err := strconv.ParseInt(strVal, 10, 64); err == nil {
-			return intVal
-		} // let terraform core handle it if we can't convert the string to an int.
+	if v == nil || v.(string) == "" {
+		return 1200
 	}
 	return v
 }
 
 func flattenComputeRouterNatTcpTransitoryIdleTimeoutSec(v interface{}, d *schema.ResourceData) interface{} {
-	// Handles the string fixed64 format
-	if strVal, ok := v.(string); ok {
-		if intVal, err := strconv.ParseInt(strVal, 10, 64); err == nil {
-			return intVal
-		} // let terraform core handle it if we can't convert the string to an int.
+	if v == nil || v.(string) == "" {
+		return 30
 	}
 	return v
 }