diff --git a/src/Length.cpp b/src/Length.cpp
index 5e5a805c67..62b7c842f8 100644
--- a/src/Length.cpp
+++ b/src/Length.cpp
@@ -302,7 +302,11 @@ int Length::inPixels(MetricsBase const & base) const
 {
 	FontInfo fi = base.font;
 	if (unit_ == Length::MU)
+		// mu is 1/18th of an em in the math symbol font
 		fi.setFamily(SYMBOL_FAMILY);
+	else
+		// Math style is only taken into account in the case of mu
+		fi.setStyle(LM_ST_TEXT);
 	return inPixels(base.textwidth, theFontMetrics(fi).em());
 }