diff --git a/src/designviewer.cpp b/src/designviewer.cpp
index 4802638e29d148aa7c2d6d90cbe4015f82d7fe1e..e8663d110d1f346236e059b905fa4a6b139c0d23 100644
--- a/src/designviewer.cpp
+++ b/src/designviewer.cpp
@@ -369,15 +369,15 @@ void DesignViewer::printLog(const QString &message)
 
 void DesignViewer::printWarn(const QString &message)
 {
-    QString escaped = message;
-    escaped.replace("'", "\'");
-    escaped.replace("\n", "\\n");
-    emscripten_run_script("alert('" + escaped.toUtf8() + "');");
+    fprintf(stderr, "WARNING:%s\n", qPrintable(message));
 }
 
 void DesignViewer::printError(const QString &message, const QString &fileName, int line)
 {
-    printWarn(message);
+    QString escaped = message;
+    escaped.replace("'", "\'");
+    escaped.replace("\n", "\\n");
+    emscripten_run_script("alert('" + escaped.toUtf8() + "');");
     emscripten_run_script("location.hash = ''; location.reload();");
 }