diff --git a/aegisub/src/command/tool.cpp b/aegisub/src/command/tool.cpp
index e7babeb1c..b668d7188 100644
--- a/aegisub/src/command/tool.cpp
+++ b/aegisub/src/command/tool.cpp
@@ -49,6 +49,7 @@
 #include "../dialog_fonts_collector.h"
 #include "../standard_paths.h" // tool_assdraw
 #include "../video_context.h" // tool_font_collector
+#include "../compat.h"
 #include "../dialog_export.h"
 #include "../dialog_resample.h"
 #include "../dialog_selection.h"
@@ -227,10 +228,16 @@ struct tool_translation_assistant : public Command {
 
 	void operator()(agi::Context *c) {
 		c->videoController->Stop();
-		DialogTranslation d(c);
-		c->translationAssistant = &d;
-		d.ShowModal();
-		c->translationAssistant = 0;
+		try {
+			DialogTranslation d(c);
+			c->translationAssistant = &d;
+			d.ShowModal();
+			c->translationAssistant = 0;
+		}
+		catch (agi::Exception const& e) {
+			c->translationAssistant = 0;
+			wxMessageBox(lagi_wxString(e.GetChainedMessage()));
+		}
 	}
 };
 
diff --git a/aegisub/src/dialog_translation.cpp b/aegisub/src/dialog_translation.cpp
index a04237337..b1df9ddab 100644
--- a/aegisub/src/dialog_translation.cpp
+++ b/aegisub/src/dialog_translation.cpp
@@ -32,6 +32,7 @@
 #include "ass_file.h"
 #include "audio_controller.h"
 #include "command/command.h"
+#include "compat.h"
 #include "help_button.h"
 #include "libresrc/libresrc.h"
 #include "persist_location.h"
@@ -157,8 +158,10 @@ DialogTranslation::DialogTranslation(agi::Context *c)
 	Bind(wxEVT_KEY_DOWN, &DialogTranslation::OnKeyDown, this);
 
 	active_line->ParseASSTags();
-	if (bad_block(active_line->Blocks[0]))
-		NextBlock();
+	if (bad_block(active_line->Blocks[0])) {
+		if (!NextBlock())
+			throw NothingToTranslate(STD_STR(_("There is nothing to translate in the file.")));
+	}
 	else
 		UpdateDisplay();
 }
diff --git a/aegisub/src/dialog_translation.h b/aegisub/src/dialog_translation.h
index e8a96a0a8..569e989ac 100644
--- a/aegisub/src/dialog_translation.h
+++ b/aegisub/src/dialog_translation.h
@@ -24,6 +24,7 @@
 #include <wx/dialog.h>
 #endif
 
+#include <libaegisub/exception.h>
 #include <libaegisub/scoped_ptr.h>
 
 namespace agi { struct Context; }
@@ -71,4 +72,6 @@ public:
 	bool PrevBlock();
 	void Commit(bool next);
 	void InsertOriginal();
+
+	DEFINE_SIMPLE_EXCEPTION_NOINNER(NothingToTranslate, agi::Exception, "dialog/translation/nothing_to_translate");
 };