I am new to using the Haskell FFI, and have been trying to implement the example in section 11.6 of the GHC user's guide. I have finally gotten to the point where my dll compiles (there is a missing space in the mainDll.h code at line 4:12) using GHC 6.6.1, and used the declare statement to expose the "adder" function in Excel VBA. My VBA Code is given below: Private Declare Function adder Lib " adder.dll" Alias "adder@8" (ByVal x As Integer, ByVal y As Integer) As Integer Private Sub test() Debug.Print adder(1, 2) End Sub My problem is this: The function works fine (the immediate window displays 3), but when I terminate Excel, I get an application error ("The instruction at ... referenced memory at ... . The memory could not be read."). Does anyone else have any experience calling Haskell from VBA that might be relevant?