diff --git a/qrenderdoc/Code/pyrenderdoc/PythonContext.cpp b/qrenderdoc/Code/pyrenderdoc/PythonContext.cpp
index b71fd9b70..3f73beb50 100644
--- a/qrenderdoc/Code/pyrenderdoc/PythonContext.cpp
+++ b/qrenderdoc/Code/pyrenderdoc/PythonContext.cpp
@@ -2275,6 +2275,64 @@ void PythonContext::LaunchDebugger(QWidget *window, PersistantConfig &config, QS
   });
 }
 
+PyParseError PythonContext::CheckPyParse(const QByteArray &script, const rdcstr &scriptNameForErrors)
+{
+  PyParseError parseError;
+
+  PyGILState_STATE gil = PyGILState_Ensure();
+
+  PyObject *ast = PyImport_ImportModule("ast");
+
+  PyObject *scriptText = PyUnicode_FromStringAndSize(script.data(), script.size());
+  PyObject *scriptName = PyUnicode_FromString(scriptNameForErrors.c_str());
+
+  PyObject *parseResult = PyObject_CallMethod(ast, "parse", "OO", scriptText, scriptName);
+
+  if(!parseResult)
+  {
+    PyObject *exObj = NULL, *valueObj = NULL, *tracebackObj = NULL;
+
+    PyErr_Fetch(&exObj, &valueObj, &tracebackObj);
+    PyErr_NormalizeException(&exObj, &valueObj, &tracebackObj);
+
+    {
+      PyObject *a;
+
+      PyObject_GetOptionalAttrString(valueObj, "lineno", &a);
+      parseError.lineno = PyLong_AsInt(a);
+      Py_XDECREF(a);
+
+      PyObject_GetOptionalAttrString(valueObj, "offset", &a);
+      parseError.offset = PyLong_AsInt(a);
+      Py_XDECREF(a);
+
+      PyObject *repr = PyObject_Str(valueObj);
+      PyObject *utf8 = PyUnicode_AsUTF8String(repr);
+      parseError.errStr = PyBytes_AsString(utf8);
+      for(int i = 1; i < parseError.offset - 1; i++)
+        parseError.errStr.insert(0, ' ');
+      parseError.errStr.insert(parseError.offset - 2, "^\n");
+
+      Py_XDECREF(repr);
+      Py_XDECREF(utf8);
+    }
+
+    Py_XDECREF(exObj);
+    Py_XDECREF(valueObj);
+    Py_XDECREF(tracebackObj);
+  }
+
+  Py_XDECREF(scriptText);
+  Py_XDECREF(scriptName);
+  Py_XDECREF(parseResult);
+
+  Py_XDECREF(ast);
+
+  PyGILState_Release(gil);
+
+  return parseError;
+}
+
 extern "C" PyThreadState *GetExecutingThreadState(PyObject *global_handle)
 {
   OutputRedirector *redirector = (OutputRedirector *)global_handle;
diff --git a/qrenderdoc/Code/pyrenderdoc/PythonContext.h b/qrenderdoc/Code/pyrenderdoc/PythonContext.h
index d1878fd6e..deb0e06da 100644
--- a/qrenderdoc/Code/pyrenderdoc/PythonContext.h
+++ b/qrenderdoc/Code/pyrenderdoc/PythonContext.h
@@ -37,6 +37,12 @@ typedef struct _object PyObject;
 typedef struct _frame PyFrameObject;
 typedef struct _ts PyThreadState;
 
+struct PyParseError
+{
+  int lineno = -1, offset = -1;
+  rdcstr errStr;
+};
+
 class PythonContext : public QObject
 {
 private:
@@ -77,6 +83,8 @@ public:
   static bool WaitForDebugger();
   static void LaunchDebugger(QWidget *window, PersistantConfig &config, QString context_location);
 
+  PyParseError CheckPyParse(const QByteArray &script, const rdcstr &scriptNameForErrors);
+
   bool CheckInterfaces(rdcstr &log);
 
   QString versionString();
diff --git a/qrenderdoc/Windows/PythonShell.cpp b/qrenderdoc/Windows/PythonShell.cpp
index c3d8ba0cb..25d5074a7 100644
--- a/qrenderdoc/Windows/PythonShell.cpp
+++ b/qrenderdoc/Windows/PythonShell.cpp
@@ -952,7 +952,42 @@ PythonShell::PythonShell(ICaptureContext &ctx, QWidget *parent)
 
   scriptEditor = new ScintillaEdit(this);
 
+  // don't repeatedly re-parse for errors. Have a reasonable timeout
+  QTimer *checkTimer = new QTimer(this);
+  checkTimer->setSingleShot(true);
+  checkTimer->setInterval(1200);
+
+  QObject::connect(checkTimer, &QTimer::timeout, [this]() {
+    PythonContext *context = new PythonContext();
+
+    setGlobals(context);
+
+    QByteArray script = scriptEditor->getText(scriptEditor->textLength() + 1);
+    PyParseError parseError = context->CheckPyParse(script, "script.py");
+
+    if(parseError.lineno >= 0)
+    {
+      sptr_t end = scriptEditor->lineLength(parseError.lineno - 1);
+      sptr_t linePos = scriptEditor->positionFromLine(parseError.lineno - 1);
+      while(QChar(QLatin1Char(script[int(linePos + end - 1)])).isSpace())
+        end--;
+      scriptEditor->setIndicatorCurrent(0);
+      scriptEditor->indicatorFillRange(linePos + parseError.offset - 1, end + 1 - parseError.offset);
+
+      scriptEditor->annotationSetText(parseError.lineno - 1, parseError.errStr.c_str());
+      scriptEditor->annotationSetVisible(ANNOTATION_BOXED);
+      scriptEditor->annotationSetStyle(parseError.lineno - 1, 100);
+    }
+
+    context->Finish();
+  });
+
+  scriptEditor->indicSetFore(0, 0x0000ff);
+
   scriptEditor->styleSetFont(STYLE_DEFAULT, Formatter::FixedFont().family().toUtf8().data());
+  scriptEditor->styleSetFont(100, Formatter::FixedFont().family().toUtf8().data());
+  scriptEditor->styleSetBack(
+      100, IsDarkTheme() ? SCINTILLA_COLOUR(175, 70, 70) : SCINTILLA_COLOUR(255, 150, 150));
 
   scriptEditor->setMarginLeft(4.0);
   scriptEditor->setMarginWidthN(0, 32.0);
@@ -992,12 +1027,21 @@ PythonShell::PythonShell(ICaptureContext &ctx, QWidget *parent)
   });
 
   QObject::connect(scriptEditor, &ScintillaEdit::modified,
-                   [this](int type, int, int, int, const QByteArray &, int, int, int) {
+                   [this, checkTimer](int type, int, int, int, const QByteArray &, int, int, int) {
                      if(type & (SC_MOD_INSERTTEXT | SC_MOD_DELETETEXT | SC_MOD_BEFOREINSERT |
                                 SC_MOD_BEFOREDELETE))
                      {
                        scriptEditor->markerDeleteAll(CURRENT_MARKER);
                        scriptEditor->markerDeleteAll(CURRENT_MARKER + 1);
+
+                       // always remove errors immediately
+                       scriptEditor->setIndicatorCurrent(0);
+                       scriptEditor->indicatorClearRange(0, scriptEditor->textLength() + 1);
+                       scriptEditor->annotationClearAll();
+
+                       // we'll reparse when this timer finishes (it will be re-started on every
+                       // change, so only N ms after the last change
+                       checkTimer->start();
                      }
                    });