diff --git a/lldb/source/Commands/CommandObjectThread.cpp b/lldb/source/Commands/CommandObjectThread.cpp
--- a/lldb/source/Commands/CommandObjectThread.cpp
+++ b/lldb/source/Commands/CommandObjectThread.cpp
@@ -2187,9 +2187,9 @@
       result.AppendError("invalid thread\n");
       return false;
     }
-    result.AppendMessageWithFormatv("json = {0}, pretty_json = {1}, file = {2}",
+    result.AppendMessageWithFormatv("json = {0}, pretty_json = {1}, file = {2}, thread = {3}",
                                     m_options.m_json, m_options.m_pretty_json,
-                                    m_options.m_output_file);
+                                    !!m_options.m_output_file, thread_sp->GetID());
     return true;
   }
 
diff --git a/lldb/test/API/commands/trace/TestTraceDumpFunctionCalls.py b/lldb/test/API/commands/trace/TestTraceDumpFunctionCalls.py
new file mode 100644
--- /dev/null
+++ b/lldb/test/API/commands/trace/TestTraceDumpFunctionCalls.py
@@ -0,0 +1,17 @@
+from intelpt_testcase import *
+from lldbsuite.test.lldbtest import *
+from lldbsuite.test.decorators import *
+
+class TestTraceDumpInfo(TraceIntelPTTestCaseBase):
+    def testDumpFunctionCalls(self):
+      self.expect("trace load -v " +
+        os.path.join(self.getSourceDir(), "intelpt-trace", "trace.json"))
+
+      self.expect("thread trace dump function-calls 2",
+        error=True, substrs=['error: no thread with index: "2"'])
+
+      self.expect("thread trace dump function-calls 1 -j",
+        substrs=['json = true, pretty_json = false, file = false, thread = 3842849'])
+
+      self.expect("thread trace dump function-calls 1 -F /tmp -J",
+        substrs=['false, pretty_json = true, file = true, thread = 3842849'])