diff --git a/src/stdlib/WebSharper.MathJS/Main.fs b/src/stdlib/WebSharper.MathJS/Main.fs
index 5c46d648..30ee8769 100644
--- a/src/stdlib/WebSharper.MathJS/Main.fs
+++ b/src/stdlib/WebSharper.MathJS/Main.fs
@@ -143,6 +143,7 @@ module Definition =
         [|
             BaseNumber.Type
             T<float>
+            T<decimal>
             T<int>
             Unit.Type
         |]
@@ -158,6 +159,7 @@ module Definition =
         [|
             BaseNumber.Type
             T<float>
+            T<decimal>
             T<int>
             Unit.Type
         |]
diff --git a/tests/WebSharper.Tests/MathJS.fs b/tests/WebSharper.Tests/MathJS.fs
index 19a34cc2..c8be1d35 100644
--- a/tests/WebSharper.Tests/MathJS.fs
+++ b/tests/WebSharper.Tests/MathJS.fs
@@ -43,6 +43,9 @@ let Tests runServerSide =
             equalMsg (MathJS.Math.Add(1., 2., 3.)) 6. "MathJS.Math.Add(1., 2., 3.) = 6"
         }
 
+        Test "MathJS add (decimal)" {
+            equalMsg (MathJS.Math.Add(1.0m, 0.1m, 2.0m, 0.2m)) 3.3m "MathJS.Math.Add(1.0m, 0.1m, 2.0m, 0.2m) = 3.3m"
+        }
             
         Test "MathJS add (fraction)" {
             let a = MathJS.Math.Fraction(0.1)
@@ -288,6 +291,12 @@ let Tests runServerSide =
             equal (floor x) 18133887298m
         }
 
+        Test "MathJS.Math.Round" {
+            let x = 18133887298.441562272235520m
+            equal (MathJS.Math.Round(x, 0m)) 18133887298m
+            equal (MathJS.Math.Round(x, 2m)) 18133887298.44m
+        }
+
         Test "Decimal comparison" {
             let x = 18133887298.441562272235520m
             let y = 18133887298.441562272237357m