diff --git a/internal/services/cosmos/cosmosdb_account_resource.go b/internal/services/cosmos/cosmosdb_account_resource.go
index 5e06d230e279..98674ac11d26 100644
--- a/internal/services/cosmos/cosmosdb_account_resource.go
+++ b/internal/services/cosmos/cosmosdb_account_resource.go
@@ -47,6 +47,26 @@ func resourceCosmosDbAccount() *pluginsdk.Resource {
 		Read:   resourceCosmosDbAccountRead,
 		Update: resourceCosmosDbAccountUpdate,
 		Delete: resourceCosmosDbAccountDelete,
+		CustomizeDiff: pluginsdk.CustomizeDiffShim(func(ctx context.Context, diff *pluginsdk.ResourceDiff, v interface{}) error {
+			caps := diff.Get("capabilities")
+			mongo34found := false
+			enableMongo := false
+			for _, cap := range caps.(*pluginsdk.Set).List() {
+				m := cap.(map[string]interface{})
+				if v, ok := m["name"].(string); ok {
+					if v == "MongoDBv3.4" {
+						mongo34found = true
+					} else if v == "EnableMongo" {
+						enableMongo = true
+					}
+				}
+			}
+
+			if mongo34found && !enableMongo {
+				return fmt.Errorf("capability EnableMongo must be enabled if MongoDBv3.4 is also enabled")
+			}
+			return nil
+		}),
 		// TODO: replace this with an importer which validates the ID during import
 		Importer: pluginsdk.DefaultImporter(),
 
diff --git a/internal/services/cosmos/cosmosdb_account_resource_test.go b/internal/services/cosmos/cosmosdb_account_resource_test.go
index 79e6b0a1d15d..5d9849e39510 100644
--- a/internal/services/cosmos/cosmosdb_account_resource_test.go
+++ b/internal/services/cosmos/cosmosdb_account_resource_test.go
@@ -3,6 +3,7 @@ package cosmos_test
 import (
 	"context"
 	"fmt"
+	"regexp"
 	"strconv"
 	"testing"
 
@@ -469,6 +470,17 @@ func TestAccCosmosDBAccount_capabilities_MongoDBv34(t *testing.T) {
 	testAccCosmosDBAccount_capabilitiesWith(t, documentdb.DatabaseAccountKindMongoDB, []string{"EnableMongo", "MongoDBv3.4"})
 }
 
+func TestAccCosmosDBAccount_capabilities_MongoDBv34_NoEnableMongo(t *testing.T) {
+	data := acceptance.BuildTestData(t, "azurerm_cosmosdb_account", "test")
+	r := CosmosDBAccountResource{}
+	data.ResourceTest(t, r, []acceptance.TestStep{
+		{
+			Config:      r.capabilities(data, documentdb.DatabaseAccountKindMongoDB, []string{"MongoDBv3.4"}),
+			ExpectError: regexp.MustCompile("capability EnableMongo must be enabled if MongoDBv3.4 is also enabled"),
+		},
+	})
+}
+
 func TestAccCosmosDBAccount_capabilities_mongoEnableDocLevelTTL(t *testing.T) {
 	testAccCosmosDBAccount_capabilitiesWith(t, documentdb.DatabaseAccountKindMongoDB, []string{"EnableMongo", "mongoEnableDocLevelTTL"})
 }
diff --git a/website/docs/r/cosmosdb_account.html.markdown b/website/docs/r/cosmosdb_account.html.markdown
index c41ba67827d9..c0f409f0a615 100644
--- a/website/docs/r/cosmosdb_account.html.markdown
+++ b/website/docs/r/cosmosdb_account.html.markdown
@@ -44,6 +44,10 @@ resource "azurerm_cosmosdb_account" "db" {
     name = "MongoDBv3.4"
   }
 
+  capabilities {
+    name = "EnableMongo"
+  }
+
   consistency_policy {
     consistency_level       = "BoundedStaleness"
     max_interval_in_seconds = 10
@@ -145,7 +149,9 @@ The following arguments are supported:
 
 `capabilities` Configures the capabilities to enable for this Cosmos DB account:
 
-* `name` - (Required) The capability to enable - Possible values are `AllowSelfServeUpgradeToMongo36`, `DisableRateLimitingResponses`, `EnableAggregationPipeline`, `EnableCassandra`, `EnableGremlin`, `EnableMongo`, `EnableTable`, `EnableServerless`, `MongoDBv3.4` and `mongoEnableDocLevelTTL`.
+* `name` - (Required) The capability to enable - Possible values are `AllowSelfServeUpgradeToMongo36`, `DisableRateLimitingResponses`, `EnableAggregationPipeline`, `EnableCassandra`, `EnableGremlin`, `EnableMongo`, `EnableTable`, `EnableServerless`, `MongoDBv3.4` and `mongoEnableDocLevelTTL`. 
+
+**NOTE:**  Setting `MongoDBv3.4` also requires setting `EnableMongo`.
 
 **NOTE:** The `prefix` and `failover_priority` fields of a location cannot be changed for the location with a failover priority of `0`.