diff --git a/schema/core_schema.go b/schema/core_schema.go
index fc2afd48..cbade25c 100644
--- a/schema/core_schema.go
+++ b/schema/core_schema.go
@@ -30,6 +30,7 @@ var (
 	v1_5  = version.Must(version.NewVersion("1.5"))
 	v1_6  = version.Must(version.NewVersion("1.6"))
 	v1_7  = version.Must(version.NewVersion("1.7"))
+	v1_8  = version.Must(version.NewVersion("1.8"))
 )
 
 // CoreModuleSchemaForVersion finds a module schema which is relevant
diff --git a/schema/functions_merge.go b/schema/functions_merge.go
index c68dc634..e0a961e5 100644
--- a/schema/functions_merge.go
+++ b/schema/functions_merge.go
@@ -6,13 +6,15 @@ package schema
 import (
 	"fmt"
 
+	"github.com/hashicorp/go-version"
 	"github.com/hashicorp/hcl-lang/schema"
 	tfmod "github.com/hashicorp/terraform-schema/module"
 )
 
 type FunctionsMerger struct {
-	coreFunctions map[string]schema.FunctionSignature
-	schemaReader  SchemaReader
+	coreFunctions    map[string]schema.FunctionSignature
+	terraformVersion *version.Version
+	schemaReader     SchemaReader
 }
 
 func NewFunctionsMerger(coreFunctions map[string]schema.FunctionSignature) *FunctionsMerger {
@@ -25,6 +27,10 @@ func (m *FunctionsMerger) SetSchemaReader(sr SchemaReader) {
 	m.schemaReader = sr
 }
 
+func (m *FunctionsMerger) SetTerraformVersion(v *version.Version) {
+	m.terraformVersion = v
+}
+
 func (m *FunctionsMerger) FunctionsForModule(meta *tfmod.Meta) (map[string]schema.FunctionSignature, error) {
 	if m.coreFunctions == nil {
 		return nil, coreFunctionsRequiredErr{}
@@ -34,6 +40,10 @@ func (m *FunctionsMerger) FunctionsForModule(meta *tfmod.Meta) (map[string]schem
 		return m.coreFunctions, nil
 	}
 
+	if m.terraformVersion.LessThan(v1_8) {
+		return m.coreFunctions, nil
+	}
+
 	mergedFunctions := make(map[string]schema.FunctionSignature, len(m.coreFunctions))
 	for fName, fSig := range m.coreFunctions {
 		mergedFunctions[fName] = *fSig.Copy()
diff --git a/schema/functions_merge_test.go b/schema/functions_merge_test.go
index 411637ef..d279366a 100644
--- a/schema/functions_merge_test.go
+++ b/schema/functions_merge_test.go
@@ -57,7 +57,32 @@ func TestFunctionsMerger_FunctionsForModule_noMeta(t *testing.T) {
 	}
 }
 
-func TestFunctionsMerger_FunctionsForModule(t *testing.T) {
+var providerSchemaWithFunctions = map[string]*tfjson.ProviderSchema{
+	"registry.terraform.io/hashicorp/test": {
+		ConfigSchema:      &tfjson.Schema{},
+		DataSourceSchemas: map[string]*tfjson.Schema{},
+		ResourceSchemas:   map[string]*tfjson.Schema{},
+		Functions: map[string]*tfjson.FunctionSignature{
+			"bar": {
+				Parameters: []*tfjson.FunctionParameter{
+					{Name: "baz", Type: cty.String, Description: "baz param"},
+				},
+				Description: "bar function",
+				ReturnType:  cty.String,
+			},
+			"alleven": {
+				VariadicParameter: &tfjson.FunctionParameter{
+					Name: "numbers",
+					Type: cty.List(cty.Number),
+				},
+				Description: "Returns true if all passed arguments are even numbers",
+				ReturnType:  cty.Bool,
+			},
+		},
+	},
+}
+
+func TestFunctionsMerger_FunctionsForModule_18(t *testing.T) {
 	coreFunctions := map[string]schema.FunctionSignature{
 		"foo": {
 			Params: []function.Parameter{
@@ -71,40 +96,13 @@ func TestFunctionsMerger_FunctionsForModule(t *testing.T) {
 	fm.SetSchemaReader(&testJsonSchemaReader{
 		ps: &tfjson.ProviderSchemas{
 			FormatVersion: "1.0",
-			Schemas: map[string]*tfjson.ProviderSchema{
-				"registry.terraform.io/hashicorp/test": {
-					ConfigSchema:      &tfjson.Schema{},
-					DataSourceSchemas: map[string]*tfjson.Schema{},
-					ResourceSchemas:   map[string]*tfjson.Schema{},
-					Functions: map[string]*tfjson.FunctionSignature{
-						"bar": {
-							Parameters: []*tfjson.FunctionParameter{
-								{Name: "baz", Type: cty.String, Description: "baz param"},
-							},
-							Description: "bar function",
-							ReturnType:  cty.String,
-						},
-						"alleven": {
-							VariadicParameter: &tfjson.FunctionParameter{
-								Name: "numbers",
-								Type: cty.List(cty.Number),
-							},
-							Description: "Returns true if all passed arguments are even numbers",
-							ReturnType:  cty.Bool,
-						},
-					},
-				},
-			},
+			Schemas:       providerSchemaWithFunctions,
 		},
 	})
+	fm.SetTerraformVersion(version.Must(version.NewVersion("1.8")))
 
 	testProvider := addr.NewDefaultProvider("test")
-	versionConstraints, err := version.NewConstraint("1.0.0")
-
-	if err != nil {
-		t.Fatalf("unexpected error: %#v", err)
-	}
-
+	versionConstraints := version.MustConstraints(version.NewConstraint("1.0.0"))
 	meta := &tfmod.Meta{
 		ProviderReferences: map[tfmod.ProviderRef]tfaddr.Provider{
 			{LocalName: "localtest"}: testProvider,
@@ -149,3 +147,36 @@ func TestFunctionsMerger_FunctionsForModule(t *testing.T) {
 		t.Fatalf("functions mismatch: %s", diff)
 	}
 }
+
+func TestFunctionsMerger_FunctionsForModule_17(t *testing.T) {
+	fm := NewFunctionsMerger(map[string]schema.FunctionSignature{})
+	fm.SetSchemaReader(&testJsonSchemaReader{
+		ps: &tfjson.ProviderSchemas{
+			FormatVersion: "1.0",
+			Schemas:       providerSchemaWithFunctions,
+		},
+	})
+	fm.SetTerraformVersion(version.Must(version.NewVersion("1.7")))
+
+	testProvider := addr.NewDefaultProvider("test")
+	versionConstraints := version.MustConstraints(version.NewConstraint("1.0.0"))
+	meta := &tfmod.Meta{
+		ProviderReferences: map[tfmod.ProviderRef]tfaddr.Provider{
+			{LocalName: "localtest"}: testProvider,
+		},
+		ProviderRequirements: tfmod.ProviderRequirements{
+			testProvider: versionConstraints,
+		},
+	}
+
+	expectedFunctions := map[string]schema.FunctionSignature{}
+
+	givenFunctions, err := fm.FunctionsForModule(meta)
+	if err != nil {
+		t.Fatalf("unexpected error: %#v", err)
+	}
+
+	if diff := cmp.Diff(expectedFunctions, givenFunctions, ctydebug.CmpOptions); diff != "" {
+		t.Fatalf("functions mismatch: %s", diff)
+	}
+}