diff --git a/bundle/definition/validation_test.go b/bundle/definition/validation_test.go
index 724679b0..a032f1a1 100644
--- a/bundle/definition/validation_test.go
+++ b/bundle/definition/validation_test.go
@@ -42,7 +42,7 @@ func TestObjectValidationValid(t *testing.T) {
 	assert.NoError(t, err)
 }
 
-func TestObjectValidationValid_CustomValidator(t *testing.T) {
+func TestObjectValidationValid_CustomValidator_ContentEncoding_base64(t *testing.T) {
 	s := `{
 		"type": "object",
 		"properties" : {
@@ -71,8 +71,43 @@ func TestObjectValidationValid_CustomValidator(t *testing.T) {
 		File: "SGVsbG8gV29ybGQhCg==",
 	}
 	valErrors, err := definition.Validate(val)
+	assert.NoError(t, err)
 	assert.Len(t, valErrors, 0, "expected no validation errors")
+
+	invalidVal := struct {
+		File string `json:"file"`
+	}{
+		File: "SGVsbG8gV29ybGQhCg===",
+	}
+	valErrors, err = definition.Validate(invalidVal)
+	assert.NoError(t, err)
+	assert.Len(t, valErrors, 1, "expected 1 validation error")
+	assert.Equal(t, "invalid base64 value: SGVsbG8gV29ybGQhCg===", valErrors[0].Error)
+}
+
+func TestObjectValidationValid_CustomValidator_ContentEncoding_InvalidEncoding(t *testing.T) {
+	s := `{
+		"type": "object",
+		"properties" : {
+			"file" : {
+				"type": "string",
+				"contentEncoding": "base65"
+			}
+		},
+		"required" : ["file"]
+	}`
+	definition := new(Schema)
+	err := json.Unmarshal([]byte(s), definition)
+
+	val := struct {
+		File string `json:"file"`
+	}{
+		File: "SGVsbG8gV29ybGQhCg==",
+	}
+	valErrors, err := definition.Validate(val)
 	assert.NoError(t, err)
+	assert.Len(t, valErrors, 1, "expected 1 validation error")
+	assert.Equal(t, "unsupported or invalid contentEncoding type of base65", valErrors[0].Error)
 }
 
 func TestObjectValidationInValidMinimum(t *testing.T) {
diff --git a/bundle/definition/validators.go b/bundle/definition/validators.go
index 18d990ce..d09f36ec 100644
--- a/bundle/definition/validators.go
+++ b/bundle/definition/validators.go
@@ -1,6 +1,9 @@
 package definition
 
 import (
+	"encoding/base64"
+	"fmt"
+
 	"github.com/qri-io/jsonschema"
 )
 
@@ -13,9 +16,22 @@ func NewContentEncoding() jsonschema.Validator {
 }
 
 // Validate implements the Validator interface for ContentEncoding
-// Currently, this is a no-op and is only used to register with the jsonschema library
-// that 'contentEncoding' is a valid property (as of writing, it isn't one of the defaults)
-func (c ContentEncoding) Validate(propPath string, data interface{}, errs *[]jsonschema.ValError) {}
+// which, as of writing, isn't included by default in the jsonschema library we consume
+func (c ContentEncoding) Validate(propPath string, data interface{}, errs *[]jsonschema.ValError) {
+	if obj, ok := data.(string); ok {
+		switch c {
+		case "base64":
+			_, err := base64.StdEncoding.DecodeString(obj)
+			if err != nil {
+				jsonschema.AddError(errs, propPath, data, fmt.Sprintf("invalid %s value: %s", c, obj))
+			}
+		// Add validation support for other encodings as needed
+		// See https://json-schema.org/latest/json-schema-validation.html#rfc.section.8.3
+		default:
+			jsonschema.AddError(errs, propPath, data, fmt.Sprintf("unsupported or invalid contentEncoding type of %s", c))
+		}
+	}
+}
 
 // NewRootSchema returns a jsonschema.RootSchema with any needed custom
 // jsonschema.Validators pre-registered