diff --git a/cli/compose/schema/bindata.go b/cli/compose/schema/bindata.go
index 3595e6ed0c..47ba45e9f4 100644
--- a/cli/compose/schema/bindata.go
+++ b/cli/compose/schema/bindata.go
@@ -510,45 +510,45 @@ bnBpPlHfjORjkTRf1wyAwiYqMXd9/G6313QfoXs6/sbZ66r6e179PwAA//8ZL3SpvkUAAA==
 
 	"/data/config_schema_v3.8.json": {
 		local:   "data/config_schema_v3.8.json",
-		size:    17835,
+		size:    17912,
 		modtime: 1518458244,
 		compressed: `
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 `,
 	},
 
diff --git a/cli/compose/schema/data/config_schema_v3.8.json b/cli/compose/schema/data/config_schema_v3.8.json
index a12a40ef8f..d56da82480 100644
--- a/cli/compose/schema/data/config_schema_v3.8.json
+++ b/cli/compose/schema/data/config_schema_v3.8.json
@@ -122,10 +122,14 @@
           }
         },
         "container_name": {"type": "string"},
-        "credential_spec": {"type": "object", "properties": {
-          "file": {"type": "string"},
-          "registry": {"type": "string"}
-        }},
+        "credential_spec": {
+          "type": "object",
+          "properties": {
+            "file": {"type": "string"},
+            "registry": {"type": "string"}
+          },
+          "additionalProperties": false
+        },
         "depends_on": {"$ref": "#/definitions/list_of_strings"},
         "devices": {"type": "array", "items": {"type": "string"}, "uniqueItems": true},
         "dns": {"$ref": "#/definitions/string_or_list"},
diff --git a/cli/compose/schema/schema_test.go b/cli/compose/schema/schema_test.go
index bb15098b28..9b29b138b3 100644
--- a/cli/compose/schema/schema_test.go
+++ b/cli/compose/schema/schema_test.go
@@ -80,17 +80,6 @@ func TestValidateAllowsXFields(t *testing.T) {
 }
 
 func TestValidateCredentialSpecs(t *testing.T) {
-	config := dict{
-		"version": "99.99",
-		"services": dict{
-			"foo": dict{
-				"image": "busybox",
-				"credential_spec": dict{
-					"config": "foobar",
-				},
-			},
-		},
-	}
 	tests := []struct {
 		version     string
 		expectedErr string
@@ -103,11 +92,23 @@ func TestValidateCredentialSpecs(t *testing.T) {
 		{version: "3.5", expectedErr: "config"},
 		{version: "3.6", expectedErr: "config"},
 		{version: "3.7", expectedErr: "config"},
+		{version: "3.8", expectedErr: "something"},
 	}
 
 	for _, tc := range tests {
 		tc := tc
 		t.Run(tc.version, func(t *testing.T) {
+			config := dict{
+				"version": "99.99",
+				"services": dict{
+					"foo": dict{
+						"image": "busybox",
+						"credential_spec": dict{
+							tc.expectedErr: "foobar",
+						},
+					},
+				},
+			}
 			err := Validate(config, tc.version)
 			if tc.expectedErr != "" {
 				assert.ErrorContains(t, err, fmt.Sprintf("Additional property %s is not allowed", tc.expectedErr))