diff --git a/src/mathed/math_gridinset.C b/src/mathed/math_gridinset.C
index 944d87dccd..658f68477b 100644
--- a/src/mathed/math_gridinset.C
+++ b/src/mathed/math_gridinset.C
@@ -268,7 +268,7 @@ string MathGridInset::eolString(int row) const
 
 	// make sure an upcoming '[' does not break anything
 	MathArray const & c = cell(index(row + 1, 0));
-	if (c.begin() && c.begin()->nucleus()->getChar() == '[')
+	if (c.size() && c.begin()->nucleus()->getChar() == '[')
 		return "\\\\[0pt]\n";
 
 	return "\\\\\n";