diff --git a/docs/ref/transforms.rst b/docs/ref/transforms.rst
index b29fa15..f90f5df 100644
--- a/docs/ref/transforms.rst
+++ b/docs/ref/transforms.rst
@@ -84,6 +84,14 @@ The provided transformation functions are:
             In:  100.0d0
             Out: "100.0"
 
+  - *hex-to-dec*
+
+    Converts a string containing an hexadecimal representation of a number
+    into its decimal representation::
+
+            In:  "deadbeef"
+            Out: "3735928559"
+            
   - *set-to-enum-array*
 
     Converts a string representing a MySQL SET into a PostgreSQL Array of
diff --git a/src/utils/transforms.lisp b/src/utils/transforms.lisp
index 4f6e1ed..497b154 100644
--- a/src/utils/transforms.lisp
+++ b/src/utils/transforms.lisp
@@ -374,7 +374,8 @@
     (null    nil)
     (string (base64:base64-string-to-string string))))
 
-(defun hex-to-dec (string)
-  (etypecase hex
+(defun hex-to-dec (hex-string)
+  (etypecase hex-string
     (null    nil)
-    (string (write-to-string (parse-integer hex :radix 16)))))
+    (integer hex-string)
+    (string (write-to-string (parse-integer hex-string :radix 16)))))