diff --git a/format-master.xml b/format-master.xml
index 7419adb..74d64c3 100755
--- a/format-master.xml
+++ b/format-master.xml
@@ -1339,9 +1339,9 @@
 	</template>
 	
 
-	<!-- Roman (upright) text inside math environments. -->
+	<!-- Roman (upright) text inside math environments.  \mathrm sounds like it's probably more correct, but doesn't retain spaces (which \textup does). -->
 	<template name="math-text" match="text" mode="math">
-		<latex>\mathrm{<xsl:apply-templates mode="math"/>}</latex>
+		<latex>\textup{<xsl:apply-templates mode="math"/>}</latex>
 		<html><xsl:apply-templates mode="math"/></html>
 	</template>
 	
