Index: src/org/openstreetmap/josm/gui/io/UploadTextComponentValidator.java
===================================================================
--- src/org/openstreetmap/josm/gui/io/UploadTextComponentValidator.java	(revision 18770)
+++ src/org/openstreetmap/josm/gui/io/UploadTextComponentValidator.java	(working copy)
@@ -48,7 +48,7 @@
         super.feedbackWarning(msg);
         if (!Objects.equals(msg, feedback.getText())) {
             feedback.setText(msg);
-            feedback.setForeground(null);
+            feedback.setForeground(WARNING_FOREGROUND);
             feedback.setBackground(WARNING_BACKGROUND);
             feedback.setBorder(WARNING_BORDER);
         }
Index: src/org/openstreetmap/josm/gui/widgets/AbstractTextComponentValidator.java
===================================================================
--- src/org/openstreetmap/josm/gui/widgets/AbstractTextComponentValidator.java	(revision 18770)
+++ src/org/openstreetmap/josm/gui/widgets/AbstractTextComponentValidator.java	(working copy)
@@ -45,6 +45,8 @@
 
     protected static final Color WARNING_COLOR = new NamedColorProperty(marktr("Input validation: warning"), new Color(0xFFA500)).get();
     protected static final Border WARNING_BORDER = BorderFactory.createLineBorder(WARNING_COLOR, 1);
+    protected static final Color WARNING_FOREGROUND = new NamedColorProperty(
+            marktr("Input validation: warning foreground"), new Color(0x000000)).get();
     protected static final Color WARNING_BACKGROUND = new NamedColorProperty(
             marktr("Input validation: warning background"), new Color(0xFFEDCC)).get();