diff --git a/pkg/apis/internal.admin.acorn.io/v1/default.go b/pkg/apis/internal.admin.acorn.io/v1/default.go
index 90b803fe3..afc27a444 100644
--- a/pkg/apis/internal.admin.acorn.io/v1/default.go
+++ b/pkg/apis/internal.admin.acorn.io/v1/default.go
@@ -10,8 +10,8 @@ import (
 	"sigs.k8s.io/controller-runtime/pkg/client"
 )
 
-func getCurrentClusterComputeClassDefault(ctx context.Context, c client.Client, projectDefaultComputeClass string) (*ClusterComputeClassInstance, error) {
-	clusterComputeClasses := ClusterComputeClassInstanceList{}
+func getCurrentClusterComputeClassDefault(ctx context.Context, c client.Client, projectDefault string) (*ClusterComputeClassInstance, error) {
+	var clusterComputeClasses ClusterComputeClassInstanceList
 	if err := c.List(ctx, &clusterComputeClasses, &client.ListOptions{}); err != nil {
 		return nil, err
 	}
@@ -30,12 +30,10 @@ func getCurrentClusterComputeClassDefault(ctx context.Context, c client.Client,
 			}
 
 			// Create a new variable that isn't being iterated on to get a pointer
-			if projectDefaultComputeClass != "" {
-				defaultCCC = z.Pointer(clusterComputeClass)
-			}
+			defaultCCC = z.Pointer(clusterComputeClass)
 		}
 
-		if clusterComputeClass.Name == projectDefaultComputeClass {
+		if clusterComputeClass.Name == projectDefault {
 			projectDefaultCCC = z.Pointer(clusterComputeClass)
 		}
 	}
@@ -47,8 +45,8 @@ func getCurrentClusterComputeClassDefault(ctx context.Context, c client.Client,
 	return defaultCCC, nil
 }
 
-func getCurrentProjectComputeClassDefault(ctx context.Context, c client.Client, projectDefaultComputeClass, namespace string) (*ProjectComputeClassInstance, error) {
-	projectComputeClasses := ProjectComputeClassInstanceList{}
+func getCurrentProjectComputeClassDefault(ctx context.Context, c client.Client, projectDefault, namespace string) (*ProjectComputeClassInstance, error) {
+	var projectComputeClasses ProjectComputeClassInstanceList
 	if err := c.List(ctx, &projectComputeClasses, &client.ListOptions{Namespace: namespace}); err != nil {
 		return nil, err
 	}
@@ -67,12 +65,10 @@ func getCurrentProjectComputeClassDefault(ctx context.Context, c client.Client,
 			}
 
 			// Create a new variable that isn't being iterated on to get a pointer
-			if projectDefaultComputeClass != "" {
-				defaultPCC = z.Pointer(projectComputeClass)
-			}
+			defaultPCC = z.Pointer(projectComputeClass)
 		}
 
-		if projectComputeClass.Name == projectDefaultComputeClass {
+		if projectDefault projectComputeClass.Name == projectDefault {
 			projectDefaultPCC = z.Pointer(projectComputeClass)
 		}
 	}
@@ -94,15 +90,18 @@ func GetDefaultComputeClass(ctx context.Context, c client.Client, namespace stri
 	pcc, err := getCurrentProjectComputeClassDefault(ctx, c, projectDefault, namespace)
 	if err != nil {
 		return "", err
-	} else if pcc != nil {
+	}
+	if pcc != nil {
 		return pcc.Name, nil
 	}
 
 	ccc, err := getCurrentClusterComputeClassDefault(ctx, c, projectDefault)
 	if err != nil {
 		return "", err
-	} else if ccc != nil {
+	}
+	if ccc != nil {
 		return ccc.Name, nil
 	}
+
 	return "", nil
 }
diff --git a/pkg/server/registry/apigroups/acorn/projects/validator.go b/pkg/server/registry/apigroups/acorn/projects/validator.go
index 8a7021fe8..e0b2da2e5 100644
--- a/pkg/server/registry/apigroups/acorn/projects/validator.go
+++ b/pkg/server/registry/apigroups/acorn/projects/validator.go
@@ -6,6 +6,8 @@ import (
 	"strings"
 
 	apiv1 "github.com/acorn-io/runtime/pkg/apis/api.acorn.io/v1"
+	"github.com/acorn-io/runtime/pkg/computeclasses"
+	apierrors "k8s.io/apimachinery/pkg/api/errors"
 	"k8s.io/apimachinery/pkg/api/meta"
 	"k8s.io/apimachinery/pkg/runtime"
 	"k8s.io/apimachinery/pkg/util/validation/field"
@@ -22,15 +24,28 @@ type Validator struct {
 	Client kclient.Client
 }
 
-func (v *Validator) Validate(_ context.Context, obj runtime.Object) field.ErrorList {
+func (v *Validator) Validate(ctx context.Context, obj runtime.Object) field.ErrorList {
 	var result field.ErrorList
 	project := obj.(*apiv1.Project)
 
-	if project.Spec.DefaultRegion != "" && !slices.Contains(project.Spec.SupportedRegions, project.Spec.DefaultRegion) && !slices.Contains(project.Spec.SupportedRegions, apiv1.AllRegions) {
-		return append(result, field.Invalid(field.NewPath("spec", "defaultRegion"), project.Spec.DefaultRegion, "default region is not in the supported regions list"))
+	if project.Spec.DefaultRegion != "" &&
+		!slices.Contains(project.Spec.SupportedRegions, project.Spec.DefaultRegion) &&
+		!slices.Contains(project.Spec.SupportedRegions, apiv1.AllRegions) {
+		result = append(result, field.Invalid(field.NewPath("spec", "defaultRegion"), project.Spec.DefaultRegion, "default region is not in the supported regions list"))
 	}
 
-	return nil
+	if defaultComputeClass := project.Spec.DefaultComputeClass; defaultComputeClass != "" {
+		if _, err := computeclasses.GetAsProjectComputeClassInstance(ctx, v.Client, project.Name, defaultComputeClass); apierrors.IsNotFound(err) {
+			// The compute class does not exist, return an invalid error
+			result = append(result, field.Invalid(field.NewPath("spec", "defaultComputeClass"), defaultComputeClass, "default compute class does not exist"))
+		} else if err != nil {
+			// Some other error occurred while trying to get the compute class, return an internal error.
+			result = append(result, field.InternalError(field.NewPath("spec", "defaultComputeClass"), err))
+		}
+		// TODO(njhale): Validate that the compute class shares the project's supported regions?
+	}
+
+	return result
 }
 
 func (v *Validator) ValidateUpdate(ctx context.Context, newObj, _ runtime.Object) field.ErrorList {