diff --git a/internal/terraform/upgrade_resource_state.go b/internal/terraform/upgrade_resource_state.go
index 07d5ea3bb8..c133f483b2 100644
--- a/internal/terraform/upgrade_resource_state.go
+++ b/internal/terraform/upgrade_resource_state.go
@@ -4,6 +4,7 @@
 package terraform
 
 import (
+	"bytes"
 	"encoding/json"
 	"fmt"
 	"log"
@@ -136,8 +137,12 @@ func upgradeResourceState(addr addrs.AbsResourceInstance, provider providers.Int
 // stripRemovedStateAttributes deletes any attributes no longer present in the
 // schema, so that the json can be correctly decoded.
 func stripRemovedStateAttributes(state []byte, ty cty.Type) []byte {
+	// we must use json.Number to avoid changing the precision of cty.Number values
+	decoder := json.NewDecoder(bytes.NewReader(state))
+	decoder.UseNumber()
+
 	jsonMap := map[string]interface{}{}
-	err := json.Unmarshal(state, &jsonMap)
+	err := decoder.Decode(&jsonMap)
 	if err != nil {
 		// we just log any errors here, and let the normal decode process catch
 		// invalid JSON.
diff --git a/internal/terraform/upgrade_resource_state_test.go b/internal/terraform/upgrade_resource_state_test.go
index bde9cfe061..ce998cf65e 100644
--- a/internal/terraform/upgrade_resource_state_test.go
+++ b/internal/terraform/upgrade_resource_state_test.go
@@ -8,6 +8,7 @@ import (
 	"testing"
 
 	"github.com/zclconf/go-cty/cty"
+	ctyjson "github.com/zclconf/go-cty/cty/json"
 )
 
 func TestStripRemovedStateAttributes(t *testing.T) {
@@ -46,6 +47,20 @@ func TestStripRemovedStateAttributes(t *testing.T) {
 			}),
 			true,
 		},
+		{
+			"has large number",
+			map[string]interface{}{
+				"a": "ok",
+				"b": nil,
+			},
+			map[string]interface{}{
+				"a": "ok",
+			},
+			cty.Object(map[string]cty.Type{
+				"a": cty.String,
+			}),
+			true,
+		},
 		{
 			"removed nested string",
 			map[string]interface{}{
@@ -149,3 +164,47 @@ func TestStripRemovedStateAttributes(t *testing.T) {
 		})
 	}
 }
+
+func TestStripRemovedStateAttributesDecoder(t *testing.T) {
+	cases := []struct {
+		name   string
+		state  string
+		expect cty.Value
+	}{
+		{
+			"removed string",
+			`{"a": "ok","b": "gone"}`,
+			cty.ObjectVal(map[string]cty.Value{
+				"a": cty.StringVal("ok"),
+			}),
+		},
+		{
+			"removed null",
+			`{"a": "ok","b": "gone"}`,
+			cty.ObjectVal(map[string]cty.Value{
+				"a": cty.StringVal("ok"),
+			}),
+		},
+		{
+			"with large number",
+			`{"a": 123456789123456789.123456789,"b": "gone"}`,
+			cty.ObjectVal(map[string]cty.Value{
+				"a": cty.MustParseNumberVal("123456789123456789.123456789"),
+			}),
+		},
+	}
+
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			upgraded := stripRemovedStateAttributes([]byte(tc.state), tc.expect.Type())
+			got, err := ctyjson.Unmarshal(upgraded, tc.expect.Type())
+			if err != nil {
+				t.Fatal(err)
+			}
+
+			if !tc.expect.RawEquals(got) {
+				t.Fatalf("expected: %#v\n      got: %#v\n", tc.expect, got)
+			}
+		})
+	}
+}