diff --git a/ext/bg/js/json-schema.js b/ext/bg/js/json-schema.js
index 8129b6d2..ab4a4817 100644
--- a/ext/bg/js/json-schema.js
+++ b/ext/bg/js/json-schema.js
@@ -154,6 +154,9 @@ class JsonSchemaProxyHandler {
         let result = JsonSchemaProxyHandler.validateSingleSchema(value, schema);
         if (result !== null) { return result; }
 
+        result = JsonSchemaProxyHandler.validateConditional(value, schema);
+        if (result !== null) { return result; }
+
         result = JsonSchemaProxyHandler.validateAllOf(value, schema);
         if (result !== null) { return result; }
 
@@ -169,6 +172,25 @@ class JsonSchemaProxyHandler {
         return null;
     }
 
+    static validateConditional(value, schema) {
+        const ifCondition = schema.if;
+        if (!JsonSchemaProxyHandler.isObject(ifCondition)) { return null; }
+
+        const thenSchema = schema.then;
+        if (JsonSchemaProxyHandler.isObject(thenSchema)) {
+            const result = JsonSchemaProxyHandler.validate(value, thenSchema);
+            if (result !== null) { return `then conditional didn't match: ${result}`; }
+        }
+
+        const elseSchema = schema.else;
+        if (JsonSchemaProxyHandler.isObject(elseSchema)) {
+            const result = JsonSchemaProxyHandler.validate(value, thenSchema);
+            if (result !== null) { return `else conditional didn't match: ${result}`; }
+        }
+
+        return null;
+    }
+
     static validateAllOf(value, schema) {
         const subSchemas = schema.allOf;
         if (!Array.isArray(subSchemas)) { return null; }