diff --git a/src/frontends/qt4/GuiExternal.cpp b/src/frontends/qt4/GuiExternal.cpp
index df0ce70f4f..9570fa0e73 100644
--- a/src/frontends/qt4/GuiExternal.cpp
+++ b/src/frontends/qt4/GuiExternal.cpp
@@ -514,6 +514,7 @@ void GuiExternal::updateContents()
 	displayscaleED->setEnabled(params_.display && !isBufferReadonly());
 	displayscaleED->setText(QString::number(params_.lyxscale));
 	displayGB->setEnabled(lyxrc.display_graphics);
+	displayscaleED->setEnabled(params_.preview_mode != PREVIEW_INSTANT);
 
 	setRotation(*angleED, *originCO, params_.rotationdata);
 
@@ -555,6 +556,7 @@ void GuiExternal::updateTemplate()
 
 	found = std::find(tr_begin, tr_end, external::Extra) != tr_end;
 	optionsGB->setEnabled(found);
+	displayscaleED->setEnabled(templ.preview_mode != PREVIEW_INSTANT);
 
 	if (!found)
 		return;
diff --git a/status.16x b/status.16x
index a9530bf1ae..f35c4e7795 100644
--- a/status.16x
+++ b/status.16x
@@ -74,6 +74,8 @@ What's new
   rather than completely over-writing it---agreeing with the behavior of our
   normal Style declarations.
 
+- Reflect external material template using Instant Preview in the dialog for
+  scaling property (bug 5628).
 
 * DOCUMENTATION AND LOCALIZATION