diff --git a/packages/proto-loader/src/index.ts b/packages/proto-loader/src/index.ts
index 9d1901b1..eab44963 100644
--- a/packages/proto-loader/src/index.ts
+++ b/packages/proto-loader/src/index.ts
@@ -391,12 +391,12 @@ export function loadFileDescriptorSet(
   options = options || {};
 
   let decodedDescriptorSet: DecodedDescriptorSet;
-  if (typeof descriptorSet === 'object') {
-    decodedDescriptorSet = descriptor.FileDescriptorSet.fromObject(
+  if (Buffer.isBuffer(descriptorSet)) {
+    decodedDescriptorSet = descriptor.FileDescriptorSet.decode(
       descriptorSet
     ) as DecodedDescriptorSet;
   } else {
-    decodedDescriptorSet = descriptor.FileDescriptorSet.decode(
+    decodedDescriptorSet = descriptor.FileDescriptorSet.fromObject(
       descriptorSet
     ) as DecodedDescriptorSet;
   }
@@ -418,7 +418,12 @@ export function loadFileDescriptorSetFile(
         return reject(err);
       }
 
-      return resolve(loadFileDescriptorSet(data, options));
+      try {
+        const jsonData = JSON.parse(data.toString());
+        return resolve(loadFileDescriptorSet(jsonData, options));
+      } catch (e) {
+        return resolve(loadFileDescriptorSet(data, options));
+      }
     });
   });
 }
diff --git a/packages/proto-loader/test/descriptor_type_test.ts b/packages/proto-loader/test/descriptor_type_test.ts
index 227b7565..7571da0a 100644
--- a/packages/proto-loader/test/descriptor_type_test.ts
+++ b/packages/proto-loader/test/descriptor_type_test.ts
@@ -103,7 +103,12 @@ describe('Descriptor types', () => {
 
   it('Can load binary-encoded proto file descriptor sets', () => {
     // This will throw if the rpc descriptor cannot be decoded
-    proto_loader.loadFileDescriptorSetFile(`${TEST_PROTO_DIR}/rpc.desc`);
+    proto_loader.loadFileDescriptorSetFile(`${TEST_PROTO_DIR}/rpc.desc.bin`);
+  });
+
+  it('Can load json file descriptor sets', () => {
+    // This will throw if the rpc descriptor JSON cannot be decoded
+    proto_loader.loadFileDescriptorSetFile(`${TEST_PROTO_DIR}/rpc.desc.json`);
   });
 
   it('Can parse plain file descriptor set objects', () => {
diff --git a/packages/proto-loader/test_protos/rpc.desc b/packages/proto-loader/test_protos/rpc.desc.bin
similarity index 100%
rename from packages/proto-loader/test_protos/rpc.desc
rename to packages/proto-loader/test_protos/rpc.desc.bin
diff --git a/packages/proto-loader/test_protos/rpc.desc.json b/packages/proto-loader/test_protos/rpc.desc.json
new file mode 100644
index 00000000..3d608e0b
--- /dev/null
+++ b/packages/proto-loader/test_protos/rpc.desc.json
@@ -0,0 +1,46 @@
+{
+  "file": [
+    {
+      "name": "test_protos/rpc.proto",
+      "messageType": [
+        {
+          "name": "MyRequest",
+          "field": [
+            {
+              "name": "path",
+              "number": 1,
+              "label": "LABEL_OPTIONAL",
+              "type": "TYPE_STRING",
+              "jsonName": "path"
+            }
+          ]
+        },
+        {
+          "name": "MyResponse",
+          "field": [
+            {
+              "name": "status",
+              "number": 2,
+              "label": "LABEL_OPTIONAL",
+              "type": "TYPE_INT32",
+              "jsonName": "status"
+            }
+          ]
+        }
+      ],
+      "service": [
+        {
+          "name": "MyService",
+          "method": [
+            {
+              "name": "MyMethod",
+              "inputType": ".MyRequest",
+              "outputType": ".MyResponse"
+            }
+          ]
+        }
+      ],
+      "syntax": "proto3"
+    }
+  ]
+}