diff --git a/src/mathed/math_gridinset.C b/src/mathed/math_gridinset.C
index f7c357f220..91613a49b1 100644
--- a/src/mathed/math_gridinset.C
+++ b/src/mathed/math_gridinset.C
@@ -700,7 +700,7 @@ void MathGridInset::write(WriteStream & os) const
 		os << eolString(row);
 	}
 	string const s = verboseHLine(rowinfo_[nrows()].lines_);
-	if (!s.empty())
+	if (!s.empty() && s != " ")
 		os << "\\\\" << s;
 }