diff --git a/src/debugger/gui/RamWidget.cxx b/src/debugger/gui/RamWidget.cxx
index c01e85c54..6a6b4079d 100644
--- a/src/debugger/gui/RamWidget.cxx
+++ b/src/debugger/gui/RamWidget.cxx
@@ -179,6 +179,10 @@ RamWidget::RamWidget(GuiObject* boss, const GUI::Font& lfont, const GUI::Font& n
   // Inputbox which will pop up when searching RAM
   const StringList labels = { "Value" };
   myInputBox = make_unique<InputTextDialog>(boss, lfont, nfont, labels, " ");
+  myInputBox->setTextFilter([](char c) {
+      return (c >= 'a' && c <= 'f') || (c >= '0' && c <= '9');
+    }
+  );
   myInputBox->setTarget(this);
 
   // Start with these buttons disabled