diff --git a/azurerm/internal/services/network/resource_arm_web_application_firewall_policy.go b/azurerm/internal/services/network/resource_arm_web_application_firewall_policy.go
index 34b6cf12ff6f..c9df5fb5efeb 100644
--- a/azurerm/internal/services/network/resource_arm_web_application_firewall_policy.go
+++ b/azurerm/internal/services/network/resource_arm_web_application_firewall_policy.go
@@ -184,7 +184,7 @@ func resourceArmWebApplicationFirewallPolicy() *schema.Resource {
 						},
 						"managed_rule_set": {
 							Type:     schema.TypeList,
-							Optional: true,
+							Required: true,
 							Elem: &schema.Resource{
 								Schema: map[string]*schema.Schema{
 									"type": {
diff --git a/azurerm/internal/services/network/tests/resource_arm_web_application_firewall_policy_test.go b/azurerm/internal/services/network/tests/resource_arm_web_application_firewall_policy_test.go
index 7dfaa2fb3d2b..aa40a00e5f64 100644
--- a/azurerm/internal/services/network/tests/resource_arm_web_application_firewall_policy_test.go
+++ b/azurerm/internal/services/network/tests/resource_arm_web_application_firewall_policy_test.go
@@ -80,14 +80,14 @@ func TestAccAzureRMWebApplicationFirewallPolicy_complete(t *testing.T) {
 					resource.TestCheckResourceAttr(data.ResourceName, "managed_rules.exclusion.1.match_variable", "RequestCookieNames"),
 					resource.TestCheckResourceAttr(data.ResourceName, "managed_rules.exclusion.1.selector", "too-much-fun"),
 					resource.TestCheckResourceAttr(data.ResourceName, "managed_rules.exclusion.1.selector_match_operator", "EndsWith"),
-					resource.TestCheckResourceAttr(data.ResourceName, "managed_rules.managed_rules_set.#", "1"),
-					resource.TestCheckResourceAttr(data.ResourceName, "managed_rules.managed_rules_set.0.type", "OWASP"),
-					resource.TestCheckResourceAttr(data.ResourceName, "managed_rules.managed_rules_set.0.version", "3.1"),
-					resource.TestCheckResourceAttr(data.ResourceName, "managed_rules.managed_rules_set.0.rule_group_override.#", "1"),
-					resource.TestCheckResourceAttr(data.ResourceName, "managed_rules.managed_rules_set.0.rule_group_override.0.rule_group_name", "REQUEST-920-PROTOCOL-ENFORCEMENT"),
-					resource.TestCheckResourceAttr(data.ResourceName, "managed_rules.managed_rules_set.0.rule_group_override.0.disabled_rules.#", "2"),
-					resource.TestCheckResourceAttr(data.ResourceName, "managed_rules.managed_rules_set.0.rule_group_override.0.disabled_rules.0", "920300"),
-					resource.TestCheckResourceAttr(data.ResourceName, "managed_rules.managed_rules_set.0.rule_group_override.0.disabled_rules.1", "920440"),
+					resource.TestCheckResourceAttr(data.ResourceName, "managed_rules.managed_rule_set.#", "1"),
+					resource.TestCheckResourceAttr(data.ResourceName, "managed_rules.managed_rule_set.0.type", "OWASP"),
+					resource.TestCheckResourceAttr(data.ResourceName, "managed_rules.managed_rule_set.0.version", "3.1"),
+					resource.TestCheckResourceAttr(data.ResourceName, "managed_rules.managed_rule_set.0.rule_group_override.#", "1"),
+					resource.TestCheckResourceAttr(data.ResourceName, "managed_rules.managed_rule_set.0.rule_group_override.0.rule_group_name", "REQUEST-920-PROTOCOL-ENFORCEMENT"),
+					resource.TestCheckResourceAttr(data.ResourceName, "managed_rules.managed_rule_set.0.rule_group_override.0.disabled_rules.#", "2"),
+					resource.TestCheckResourceAttr(data.ResourceName, "managed_rules.managed_rule_set.0.rule_group_override.0.disabled_rules.0", "920300"),
+					resource.TestCheckResourceAttr(data.ResourceName, "managed_rules.managed_rule_set.0.rule_group_override.0.disabled_rules.1", "920440"),
 					resource.TestCheckResourceAttr(data.ResourceName, "policy_settings.enabled", "true"),
 					resource.TestCheckResourceAttr(data.ResourceName, "policy_settings.mode", "Prevention"),
 				),
@@ -216,6 +216,13 @@ resource "azurerm_web_application_firewall_policy" "test" {
   name                = "acctestwafpolicy-%d"
   resource_group_name = azurerm_resource_group.test.name
   location            = azurerm_resource_group.test.location
+
+  managed_rules {
+    managed_rule_set {
+      type    = "OWASP"
+      version = "3.1"
+    }
+  }
 }
 `, data.RandomInteger, data.Locations.Primary, data.RandomInteger)
 }
@@ -296,7 +303,7 @@ resource "azurerm_web_application_firewall_policy" "test" {
       selector_match_operator = "EndsWith"
     }
 
-    managed_rules_set {
+    managed_rule_set {
       type    = "OWASP"
       version = "3.1"
 
diff --git a/website/docs/r/web_application_firewall_policy.html.markdown b/website/docs/r/web_application_firewall_policy.html.markdown
index 4020a1dcbae0..b1ee28367c72 100644
--- a/website/docs/r/web_application_firewall_policy.html.markdown
+++ b/website/docs/r/web_application_firewall_policy.html.markdown
@@ -87,7 +87,7 @@ resource "azurerm_web_application_firewall_policy" "example" {
       selector_match_operator = "EndsWith"
     }
 
-    managed_rules_set {
+    managed_rule_set {
       rule_set_type    = "OWASP"
       rule_set_version = "3.1"
       rule_group_override {
@@ -169,7 +169,7 @@ The `managed_rules` block supports the following:
 
 * `exclusion` - (Optional) One or more `exclusion` block defined below.
 
-* `managed_rules_set` - (Optional) One or more `managed_rules_set` block defined below.
+* `managed_rule_set` - (Optional) One or more `managed_rule_set` block defined below.
 
 ---
 
@@ -183,7 +183,7 @@ The `exclusion` block supports the following:
 
 ---
 
-The `managed_rules_set` block supports the following:
+The `managed_rule_set` block supports the following:
 
 * `type` - (Required) The rule set type.