diff --git a/src/Informedica.Utils.Lib/BCL/DateTime.fs b/src/Informedica.Utils.Lib/BCL/DateTime.fs
index 7581fa7..9085eaf 100644
--- a/src/Informedica.Utils.Lib/BCL/DateTime.fs
+++ b/src/Informedica.Utils.Lib/BCL/DateTime.fs
@@ -20,7 +20,7 @@ module DateTime =
 
 
     /// Create a date from a year, month and day
-    let create yr mo ds = DateTime(yr, mo, ds)
+    let create (yr : int) mo ds = DateTime(yr, mo, ds)
 
 
     /// Create a DateTime from Now
@@ -34,7 +34,7 @@ module DateTime =
 
     /// Try to create a DateTime from a year, month and day option.
     /// When one is None, None is returned
-    let optionToDate yr mo dy =
+    let optionToDate (yr : int option) mo dy =
         match yr, mo, dy with
         | Some y, Some m, Some d -> DateTime(y, m, d) |> Some
         | _ -> None
diff --git a/src/Informedica.Utils.Lib/BCL/Decimal.fs b/src/Informedica.Utils.Lib/BCL/Decimal.fs
index 6a9a0a4..a04403e 100644
--- a/src/Informedica.Utils.Lib/BCL/Decimal.fs
+++ b/src/Informedica.Utils.Lib/BCL/Decimal.fs
@@ -23,7 +23,7 @@ module Decimal =
 
     /// Get the double value of a string
     /// using `InvariantCulture`
-    let parse s = Decimal.Parse(s, CultureInfo.InvariantCulture)
+    let parse (s : string) = Decimal.Parse(s, CultureInfo.InvariantCulture)
 
 
     /// Get a `float Option` from a string
diff --git a/src/Informedica.Utils.Lib/BCL/Double.fs b/src/Informedica.Utils.Lib/BCL/Double.fs
index 04c7ca6..1d4e30e 100644
--- a/src/Informedica.Utils.Lib/BCL/Double.fs
+++ b/src/Informedica.Utils.Lib/BCL/Double.fs
@@ -47,7 +47,7 @@ module Double =
 
     /// Get the double value of a string
     /// using `InvariantCulture`
-    let parse s = Double.Parse(s, CultureInfo.InvariantCulture)
+    let parse (s : string) = Double.Parse(s, CultureInfo.InvariantCulture)
 
 
     /// Get a `float Option` from a string
diff --git a/src/Informedica.Utils.Lib/BCL/Int32.fs b/src/Informedica.Utils.Lib/BCL/Int32.fs
index 360a25c..2b450f0 100644
--- a/src/Informedica.Utils.Lib/BCL/Int32.fs
+++ b/src/Informedica.Utils.Lib/BCL/Int32.fs
@@ -9,7 +9,7 @@ module Int32 =
 
 
     /// Parses a string to an Int32. If the string cannot be parsed, an exception is thrown.
-    let parse s =
+    let parse (s: string) =
         try
         Int32.Parse(s, CultureInfo.InvariantCulture)
         with
diff --git a/src/Shared/Domain.fs b/src/Shared/Domain.fs
index 335c113..1a26d94 100644
--- a/src/Shared/Domain.fs
+++ b/src/Shared/Domain.fs
@@ -158,9 +158,9 @@ module Utils =
         let get = apply id
 
 
-        let optionToDate yr mo dy =
+        let optionToDate (yr : int option) mo dy =
             match yr, mo, dy with
-            | Some y, Some m, Some d -> new DateTime(y, m, d) |> Some
+            | Some y, Some m, Some d -> DateTime(y, m, d) |> Some
             | _ -> None