diff --git a/src/frontends/qt4/GuiSpellchecker.cpp b/src/frontends/qt4/GuiSpellchecker.cpp
index 0bcd8f1020..5a57971c47 100644
--- a/src/frontends/qt4/GuiSpellchecker.cpp
+++ b/src/frontends/qt4/GuiSpellchecker.cpp
@@ -430,6 +430,8 @@ void GuiSpellchecker::replace(docstring const & replacement)
 	LYXERR(Debug::GUI, "GuiSpellchecker::replace("
 			   << to_utf8(replacement) << ")");
 	BufferView * bv = const_cast<BufferView *>(bufferview());
+	if (!bv->cursor().inTexted())
+		return;
 	cap::replaceSelectionWithString(bv->cursor(), replacement, true);
 	bv->buffer().markDirty();
 	// If we used an LFUN, we would not need that
diff --git a/status.16x b/status.16x
index 260018f11c..150151ed6f 100644
--- a/status.16x
+++ b/status.16x
@@ -129,8 +129,11 @@ What's new
 - Fix assertion when pressing down arrow in the command buffer while
   the history is empty (bug 6001).
 
-- Fix assertion when selecting with Shift-button in math editor (bug
-  6026).
+- Fix assertion when selecting with Shift-button in math editor (bugs
+  5046 and 6026).
+
+- Fix assertion when starting spellchecker in math mode and clicking 
+  "replace" (bug 6013)
 
 - Make Tools>Statistics ignore Note insets and inactive branches
   (bug 2566).