diff --git a/cli/clidisplay/resources.go b/cli/clidisplay/resources.go
index e19c3e3..f7eab6e 100644
--- a/cli/clidisplay/resources.go
+++ b/cli/clidisplay/resources.go
@@ -43,7 +43,6 @@ func WorkspaceTags(writer io.Writer, tags types.TagBlocks) hcl.Diagnostics {
 
 func Parameters(writer io.Writer, params []types.Parameter, files map[string]*hcl.File) {
 	tableWriter := table.NewWriter()
-	// tableWriter.SetTitle("Parameters")
 	tableWriter.SetStyle(table.StyleLight)
 	tableWriter.Style().Options.SeparateColumns = false
 	row := table.Row{"Parameter"}
@@ -54,20 +53,14 @@ func Parameters(writer io.Writer, params []types.Parameter, files map[string]*hc
 		if p.FormType == provider.ParameterFormTypeMultiSelect {
 			_ = json.Unmarshal([]byte(strVal), &selections)
 		}
-		// value := p.Value.Value
-		//
-		// if value.IsNull() {
-		//	strVal = "null"
-		// } else if !p.Value.Value.IsKnown() {
-		//	strVal = "unknown"
-		// } else if value.Type().Equals(cty.String) {
-		//	strVal = value.AsString()
-		// } else {
-		//	strVal = value.GoString()
-		//}
+
+		dp := p.DisplayName
+		if p.DisplayName == "" {
+			dp = p.Name
+		}
 
 		tableWriter.AppendRow(table.Row{
-			fmt.Sprintf("(%s) %s: %s\n%s", p.DisplayName, p.Name, p.Description, formatOptions(selections, p.Options)),
+			fmt.Sprintf("(%s) %s: %s\n%s", dp, p.Name, p.Description, formatOptions(selections, p.Options)),
 		})
 
 		if hcl.Diagnostics(p.Diagnostics).HasErrors() {
diff --git a/extract/parameter.go b/extract/parameter.go
index 198173c..222807d 100644
--- a/extract/parameter.go
+++ b/extract/parameter.go
@@ -50,10 +50,12 @@ func ParameterFromBlock(block *terraform.Block) (*types.Parameter, hcl.Diagnosti
 
 	pVal := richParameterValue(block)
 
-	def := types.StringLiteral("")
+	requiredValue := true
+	def := types.NullString()
 	defAttr := block.GetAttribute("default")
 	if !defAttr.IsNil() {
 		def = types.ToHCLString(block, defAttr)
+		requiredValue = false
 	}
 
 	ftmeta := optionalString(block, "styling")
@@ -77,7 +79,7 @@ func ParameterFromBlock(block *terraform.Block) (*types.Parameter, hcl.Diagnosti
 			Icon:         optionalString(block, "icon"),
 			Options:      make([]*types.ParameterOption, 0),
 			Validations:  make([]*types.ParameterValidation, 0),
-			Required:     optionalBoolean(block, "required"),
+			Required:     requiredValue,
 			DisplayName:  optionalString(block, "display_name"),
 			Order:        optionalInteger(block, "order"),
 			Ephemeral:    optionalBoolean(block, "ephemeral"),
@@ -138,40 +140,10 @@ func ParameterFromBlock(block *terraform.Block) (*types.Parameter, hcl.Diagnosti
 		p.Validations = append(p.Validations, &valid)
 	}
 
-	ctyType, err := p.CtyType()
-	if err != nil {
-		paramTypeDiag := &hcl.Diagnostic{
-			Severity: hcl.DiagError,
-			Summary:  fmt.Sprintf("Invalid parameter type %q", p.Type),
-			Detail:   err.Error(),
-			Context:  &block.HCLBlock().DefRange,
-		}
-
-		if attr := block.GetAttribute("type"); attr != nil && !attr.IsNil() {
-			paramTypeDiag.Subject = &attr.HCLAttribute().Range
-			paramTypeDiag.Expression = attr.HCLAttribute().Expr
-			paramTypeDiag.EvalContext = block.Context().Inner()
-		}
-		diags = diags.Append(paramTypeDiag)
-		p.FormType = provider.ParameterFormTypeError
-	}
-
-	if ctyType != cty.NilType && pVal.Value.Type().Equals(cty.String) {
-		// TODO: Wish we could support more types, but only string types are
-		// allowed.
-		//nolint:gocritic // string type asserted
-		valStr := pVal.Value.AsString()
-		// Apply validations to the parameter value
-		for _, v := range p.Validations {
-			if err := v.Valid(string(pType), valStr); err != nil {
-				diags = diags.Append(&hcl.Diagnostic{
-					Severity:   hcl.DiagError,
-					Summary:    fmt.Sprintf("Paramater validation failed for value %q", valStr),
-					Detail:     err.Error(),
-					Expression: pVal.ValueExpr,
-				})
-			}
-		}
+	if !diags.HasErrors() {
+		// Only do this validation if the parameter is valid, as if some errors
+		// exist, then this is likely to fail be excess information.
+		diags = diags.Extend(p.Valid(p.Value))
 	}
 
 	usageDiags := ParameterUsageDiagnostics(p)
@@ -189,7 +161,9 @@ func ParameterFromBlock(block *terraform.Block) (*types.Parameter, hcl.Diagnosti
 func ParameterUsageDiagnostics(p types.Parameter) hcl.Diagnostics {
 	valErr := "The value of a parameter is required to be sourced (default or input) for the parameter to function."
 	var diags hcl.Diagnostics
-	if !p.Value.Valid() {
+	if p.Value.Value.IsNull() {
+		// Allow null values
+	} else if !p.Value.Valid() {
 		diags = diags.Append(&hcl.Diagnostic{
 			Severity:   hcl.DiagError,
 			Summary:    "Parameter value is not valid",
@@ -244,7 +218,6 @@ func ParameterValidationFromBlock(block *terraform.Block) (types.ParameterValida
 		Min:       nullableInteger(block, "min"),
 		Max:       nullableInteger(block, "max"),
 		Monotonic: nullableString(block, "monotonic"),
-		Invalid:   nullableBoolean(block, "invalid"),
 	}
 
 	return p, diags
@@ -477,6 +450,14 @@ func richParameterValue(block *terraform.Block) types.HCLString {
 
 	val, diags := valRef.Value(block.Context().Inner())
 	source := hclext.CreateDotReferenceFromTraversal(valRef.Traversal)
+
+	// If no value attribute exists, then the value is `null`.
+	if diags.HasErrors() && diags[0].Summary == "Unsupported attribute" {
+		s := types.NullString()
+		s.Source = &source
+		return s
+	}
+
 	return types.HCLString{
 		Value:      val,
 		ValueDiags: diags,
diff --git a/extract/state.go b/extract/state.go
index 048ae85..5e1bf7b 100644
--- a/extract/state.go
+++ b/extract/state.go
@@ -74,7 +74,7 @@ func ParameterFromState(block *tfjson.StateResource) (types.Parameter, error) {
 			Icon:         st.optionalString("icon"),
 			Options:      options,
 			Validations:  validations,
-			Required:     st.optionalBool("required"),
+			Required:     !st.optionalBool("optional"),
 			DisplayName:  st.optionalString("display_name"),
 			Order:        st.optionalInteger("order"),
 			Ephemeral:    st.optionalBool("ephemeral"),
diff --git a/go.mod b/go.mod
index 634edb1..51c118b 100644
--- a/go.mod
+++ b/go.mod
@@ -7,15 +7,18 @@ require (
 	github.com/aquasecurity/trivy v0.58.2
 	github.com/coder/guts v1.0.2-0.20250227211802-139809366a22
 	github.com/coder/serpent v0.10.0
-	github.com/coder/terraform-provider-coder/v2 v2.4.0-pre1.0.20250417100258-c86bb5c3ddcd
+	github.com/coder/terraform-provider-coder/v2 v2.4.0-pre1.0.20250506184715-e011f733bf27
 	github.com/coder/websocket v1.8.13
 	github.com/go-chi/chi v4.1.2+incompatible
+	github.com/hashicorp/go-cty v1.4.1-0.20200414143053-d3edf31b6320
 	github.com/hashicorp/go-version v1.7.0
 	github.com/hashicorp/hc-install v0.9.2
 	github.com/hashicorp/hcl/v2 v2.23.0
 	github.com/hashicorp/terraform-exec v0.23.0
 	github.com/hashicorp/terraform-json v0.24.0
+	github.com/hashicorp/terraform-plugin-sdk/v2 v2.36.1
 	github.com/jedib0t/go-pretty/v6 v6.6.7
+	github.com/quasilyte/go-ruleguard/dsl v0.3.22
 	github.com/stretchr/testify v1.10.0
 	github.com/zclconf/go-cty v1.16.2
 	golang.org/x/xerrors v0.0.0-20240903120638-7835f813f4da
@@ -69,7 +72,6 @@ require (
 	github.com/googleapis/gax-go/v2 v2.14.1 // indirect
 	github.com/hashicorp/errwrap v1.1.0 // indirect
 	github.com/hashicorp/go-cleanhttp v0.5.2 // indirect
-	github.com/hashicorp/go-cty v1.4.1-0.20200414143053-d3edf31b6320 // indirect
 	github.com/hashicorp/go-getter v1.7.8 // indirect
 	github.com/hashicorp/go-hclog v1.6.3 // indirect
 	github.com/hashicorp/go-multierror v1.1.1 // indirect
@@ -79,7 +81,6 @@ require (
 	github.com/hashicorp/logutils v1.0.0 // indirect
 	github.com/hashicorp/terraform-plugin-go v0.26.0 // indirect
 	github.com/hashicorp/terraform-plugin-log v0.9.0 // indirect
-	github.com/hashicorp/terraform-plugin-sdk/v2 v2.36.1 // indirect
 	github.com/jmespath/go-jmespath v0.4.1-0.20220621161143-b0104c826a24 // indirect
 	github.com/klauspost/compress v1.17.11 // indirect
 	github.com/lucasb-eyer/go-colorful v1.2.0 // indirect
@@ -98,7 +99,6 @@ require (
 	github.com/pion/udp v0.1.4 // indirect
 	github.com/planetscale/vtprotobuf v0.6.1-0.20240319094008-0393e58bdf10 // indirect
 	github.com/pmezard/go-difflib v1.0.1-0.20181226105442-5d4384ee4fb2 // indirect
-	github.com/quasilyte/go-ruleguard/dsl v0.3.22 // indirect
 	github.com/rivo/uniseg v0.4.7 // indirect
 	github.com/robfig/cron/v3 v3.0.1 // indirect
 	github.com/samber/lo v1.49.1 // indirect
diff --git a/go.sum b/go.sum
index 3cdb559..4e42b90 100644
--- a/go.sum
+++ b/go.sum
@@ -718,8 +718,8 @@ github.com/coder/pretty v0.0.0-20230908205945-e89ba86370e0 h1:3A0ES21Ke+FxEM8CXx
 github.com/coder/pretty v0.0.0-20230908205945-e89ba86370e0/go.mod h1:5UuS2Ts+nTToAMeOjNlnHFkPahrtDkmpydBen/3wgZc=
 github.com/coder/serpent v0.10.0 h1:ofVk9FJXSek+SmL3yVE3GoArP83M+1tX+H7S4t8BSuM=
 github.com/coder/serpent v0.10.0/go.mod h1:cZFW6/fP+kE9nd/oRkEHJpG6sXCtQ+AX7WMMEHv0Y3Q=
-github.com/coder/terraform-provider-coder/v2 v2.4.0-pre1.0.20250417100258-c86bb5c3ddcd h1:FsIG6Fd0YOEK7D0Hl/CJywRA+Y6Gd5RQbSIa2L+/BmE=
-github.com/coder/terraform-provider-coder/v2 v2.4.0-pre1.0.20250417100258-c86bb5c3ddcd/go.mod h1:56/KdGYaA+VbwXJbTI8CA57XPfnuTxN8rjxbR34PbZw=
+github.com/coder/terraform-provider-coder/v2 v2.4.0-pre1.0.20250506184715-e011f733bf27 h1:CLJwMqst39+wfFehYQzVOiG5uXUtC5fbAZ3/EpxOWos=
+github.com/coder/terraform-provider-coder/v2 v2.4.0-pre1.0.20250506184715-e011f733bf27/go.mod h1:2kaBpn5k9ZWtgKq5k4JbkVZG9DzEqR4mJSmpdshcO+s=
 github.com/coder/websocket v1.8.13 h1:f3QZdXy7uGVz+4uCJy2nTZyM0yTBj8yANEHhqlXZ9FE=
 github.com/coder/websocket v1.8.13/go.mod h1:LNVeNrXQZfe5qhS9ALED3uA+l5pPqvwXg3CKoDBB2gs=
 github.com/containerd/log v0.1.0 h1:TCJt7ioM2cr/tfR8GPbGf9/VRAX8D2B4PjzCpfX540I=
diff --git a/preview_test.go b/preview_test.go
index 5bba3a9..a72dfab 100644
--- a/preview_test.go
+++ b/preview_test.go
@@ -211,6 +211,16 @@ func Test_Extract(t *testing.T) {
 			unknownTags: []string{},
 			params:      map[string]assertParam{},
 		},
+		{
+			name:        "empty default",
+			dir:         "emptydefault",
+			expTags:     map[string]string{},
+			input:       preview.Input{},
+			unknownTags: []string{},
+			params: map[string]assertParam{
+				"word": ap(),
+			},
+		},
 		{
 			name:    "many modules",
 			dir:     "manymodules",
diff --git a/site/src/types/preview.ts b/site/src/types/preview.ts
index 0d19c4d..fd8fa38 100644
--- a/site/src/types/preview.ts
+++ b/site/src/types/preview.ts
@@ -73,7 +73,6 @@ export interface ParameterValidation {
     readonly validation_min: number | null;
     readonly validation_max: number | null;
     readonly validation_monotonic: string | null;
-    readonly validation_invalid: boolean | null;
 }
 
 // From web/session.go
diff --git a/testdata/emptydefault/main.tf b/testdata/emptydefault/main.tf
new file mode 100644
index 0000000..baa398e
--- /dev/null
+++ b/testdata/emptydefault/main.tf
@@ -0,0 +1,26 @@
+terraform {
+  required_providers {
+    coder = {
+      source = "coder/coder"
+      version = "2.4.0-pre0"
+    }
+  }
+}
+
+data "coder_parameter" "word" {
+  name        = "word"
+  description = "Select something"
+  type        = "string"
+  order       = 1
+  # No default selected
+
+  option {
+    name  = "Bird"
+    value = "bird"
+    description = "An animal that can fly."
+  }
+  option {
+    name  = "Boat"
+    value = "boat"
+  }
+}
diff --git a/testdata/emptydefault/skipe2e b/testdata/emptydefault/skipe2e
new file mode 100644
index 0000000..bc530d8
--- /dev/null
+++ b/testdata/emptydefault/skipe2e
@@ -0,0 +1 @@
+Skipping until https://github.com/coder/terraform-provider-coder/pull/381 is merged and released
diff --git a/types/convert.go b/types/convert.go
new file mode 100644
index 0000000..3d395e5
--- /dev/null
+++ b/types/convert.go
@@ -0,0 +1,90 @@
+package types
+
+import (
+	"github.com/aquasecurity/trivy/pkg/iac/terraform"
+	hcty "github.com/hashicorp/go-cty/cty"
+	"github.com/hashicorp/hcl/v2"
+	"github.com/hashicorp/terraform-plugin-sdk/v2/diag"
+
+	"github.com/coder/terraform-provider-coder/v2/provider"
+)
+
+func providerValidations(vals []*ParameterValidation) []provider.Validation {
+	cpy := make([]provider.Validation, 0, len(vals))
+	for _, val := range vals {
+		cpy = append(cpy, providerValidation(val))
+	}
+	return cpy
+}
+
+func providerValidation(v *ParameterValidation) provider.Validation {
+	return provider.Validation{
+		Min:         int(orZero(v.Min)),
+		MinDisabled: v.Min == nil,
+		Max:         int(orZero(v.Max)),
+		MaxDisabled: v.Max == nil,
+		Monotonic:   orZero(v.Monotonic),
+		Regex:       orZero(v.Regex),
+		Error:       v.Error,
+	}
+}
+
+func providerOptions(opts []*ParameterOption) []provider.Option {
+	cpy := make([]provider.Option, 0, len(opts))
+	for _, opt := range opts {
+		cpy = append(cpy, providerOption(opt))
+	}
+	return cpy
+}
+
+func providerOption(opt *ParameterOption) provider.Option {
+	return provider.Option{
+		Name:        opt.Name,
+		Description: opt.Description,
+		Value:       opt.Value.AsString(),
+		Icon:        opt.Icon,
+	}
+}
+
+func hclDiagnostics(diagnostics diag.Diagnostics, source *terraform.Block) hcl.Diagnostics {
+	cpy := make(hcl.Diagnostics, 0, len(diagnostics))
+	for _, d := range diagnostics {
+		cpy = append(cpy, hclDiagnostic(d, source))
+	}
+	return cpy
+}
+
+func hclDiagnostic(d diag.Diagnostic, source *terraform.Block) *hcl.Diagnostic {
+	sev := hcl.DiagInvalid
+	switch d.Severity {
+	case diag.Error:
+		sev = hcl.DiagError
+	case diag.Warning:
+		sev = hcl.DiagWarning
+	}
+
+	// This is an imperfect way to finding the source code of the error. There is 2
+	// different `cty` types at place here, the hashicorp fork and the original. So a
+	// more general solution is difficult. This is good enough for now to add more
+	// context to an error.
+	var subject *hcl.Range
+	if len(d.AttributePath) == 1 && source != nil {
+		if attr, ok := d.AttributePath[0].(hcty.GetAttrStep); ok {
+			src := source.GetAttribute(attr.Name)
+			if src != nil {
+				subject = &(src.HCLAttribute().Range)
+			}
+		}
+	}
+
+	return &hcl.Diagnostic{
+		Severity:    sev,
+		Summary:     d.Summary,
+		Detail:      d.Detail,
+		Subject:     subject,
+		Context:     nil,
+		Expression:  nil,
+		EvalContext: nil,
+		Extra:       nil,
+	}
+}
diff --git a/types/enum.go b/types/enum.go
index ab29945..190668b 100644
--- a/types/enum.go
+++ b/types/enum.go
@@ -3,9 +3,12 @@ package types
 import (
 	"fmt"
 	"strings"
+
+	"github.com/coder/terraform-provider-coder/v2/provider"
 )
 
-type ParameterType string
+// TODO: Just use the provider type directly.
+type ParameterType provider.OptionType
 
 const (
 	ParameterTypeString     ParameterType = "string"
diff --git a/types/parameter.go b/types/parameter.go
index f1f07b0..ab15a6f 100644
--- a/types/parameter.go
+++ b/types/parameter.go
@@ -6,6 +6,7 @@ import (
 	"strings"
 
 	"github.com/aquasecurity/trivy/pkg/iac/terraform"
+	"github.com/hashicorp/hcl/v2"
 	"github.com/zclconf/go-cty/cty"
 
 	"github.com/coder/terraform-provider-coder/v2/provider"
@@ -73,7 +74,6 @@ type ParameterValidation struct {
 	Min       *int64  `json:"validation_min"`
 	Max       *int64  `json:"validation_max"`
 	Monotonic *string `json:"validation_monotonic"`
-	Invalid   *bool   `json:"validation_invalid"`
 }
 
 type ParameterStyling struct {
@@ -82,23 +82,6 @@ type ParameterStyling struct {
 	Label       *string `json:"label,omitempty"`
 }
 
-// Valid takes the type of the value and the value itself and returns an error
-// if the value is invalid.
-func (v ParameterValidation) Valid(typ string, value string) error {
-	// TODO: Validate typ is the enum?
-	// Use the provider.Validation struct to validate the value to be
-	// consistent with the provider.
-	return (&provider.Validation{
-		Min:         int(orZero(v.Min)),
-		MinDisabled: v.Min == nil,
-		Max:         int(orZero(v.Max)),
-		MaxDisabled: v.Max == nil,
-		Monotonic:   orZero(v.Monotonic),
-		Regex:       orZero(v.Regex),
-		Error:       v.Error,
-	}).Valid(typ, value)
-}
-
 type ParameterOption struct {
 	Name        string    `json:"name"`
 	Description string    `json:"description"`
@@ -106,6 +89,45 @@ type ParameterOption struct {
 	Icon        string    `json:"icon"`
 }
 
+func (r *ParameterData) Valid(value HCLString) hcl.Diagnostics {
+	var defPtr *string
+
+	if r.DefaultValue.Valid() && r.DefaultValue.IsKnown() {
+		def := r.DefaultValue.AsString()
+		defPtr = &def
+	}
+
+	var valuePtr *string
+	// TODO: What to do if it is not valid?
+	if value.Valid() {
+		val := value.AsString()
+		valuePtr = &val
+	}
+
+	_, diag := (&provider.Parameter{
+		Name:        r.Name,
+		DisplayName: r.DisplayName,
+		Description: r.Description,
+		Type:        provider.OptionType(r.Type),
+		FormType:    r.FormType,
+		Mutable:     r.Mutable,
+		Default:     defPtr,
+		Icon:        r.Icon,
+		Option:      providerOptions(r.Options),
+		Validation:  providerValidations(r.Validations),
+		Optional:    !r.Required,
+		Order:       int(r.Order),
+		Ephemeral:   r.Ephemeral,
+	}).ValidateInput(valuePtr, nil) // TODO: Pass in previous value
+
+	if diag.HasError() {
+		// TODO: We can take the attr path and decorate the error with
+		//   source information.
+		return hclDiagnostics(diag, r.Source)
+	}
+	return nil
+}
+
 // CtyType returns the cty.Type for the ParameterData.
 // A fixed set of types are supported.
 func (r *ParameterData) CtyType() (cty.Type, error) {
diff --git a/types/value.go b/types/value.go
index 37f862b..e26087b 100644
--- a/types/value.go
+++ b/types/value.go
@@ -73,6 +73,14 @@ func StringLiteral(s string) HCLString {
 	}
 }
 
+func NullString() HCLString {
+	v := cty.NullVal(cty.String)
+	return HCLString{
+		Value:     v,
+		ValueExpr: &hclsyntax.LiteralValueExpr{Val: v},
+	}
+}
+
 // AsString is a safe function. It will always return a string.
 // The caller should check if this value is Valid and known before
 // calling this function.