diff --git a/src/DTS/DTTdeBruijn.hs b/src/DTS/DTTdeBruijn.hs
index bae79700..ab21860e 100644
--- a/src/DTS/DTTdeBruijn.hs
+++ b/src/DTS/DTTdeBruijn.hs
@@ -338,7 +338,7 @@ instance SimpleText Signature where
 instance Typeset Signature where
   toTeX = (LazyT.intercalate ",") . (map (\(nm,tm) -> LazyT.concat [nm, ":", toTeX tm])) . reverse
 instance MathML Signature where
-  toMathML = (LazyT.intercalate "<mo>,<mo>") . (map (\(nm,tm) -> LazyT.concat ["<mrow><mo>", nm, "</mo><mo>:</mo>", toMathML tm, "</mrow>"])) . reverse
+  toMathML = (LazyT.intercalate "<mo>,</mo>") . (map (\(nm,tm) -> LazyT.concat ["<mrow><mo>", nm, "</mo><mo>:</mo>", toMathML tm, "</mrow>"])) . reverse
 
 -- | A context is a list of preterms
 type Context = [Preterm]
diff --git a/src/DTS/DTTwithName.hs b/src/DTS/DTTwithName.hs
index 7b2d1325..59c7f111 100644
--- a/src/DTS/DTTwithName.hs
+++ b/src/DTS/DTTwithName.hs
@@ -395,7 +395,7 @@ instance SimpleText Signature where
 instance Typeset Signature where
   toTeX = (T.intercalate ",") . (map (\(nm,tm) -> T.concat [nm, ":", toTeX tm])) . reverse
 instance MathML Signature where
-  toMathML = (T.intercalate "<mo>,<mo>") . (map (\(nm,tm) -> T.concat ["<mrow><mo>", nm, "</mo><mo>:</mo>", toMathML tm, "</mrow>"])) . reverse
+  toMathML = (T.intercalate "<mo>,</mo>") . (map (\(nm,tm) -> T.concat ["<mrow><mo>", nm, "</mo><mo>:</mo>", toMathML tm, "</mrow>"])) . reverse
 
 -- | A context is a list of pairs of a variable and a preterm.
 type Context = [(VarName, Preterm)]