diff --git a/common/Types.hs b/common/Types.hs
index 00e3aaa..65296c4 100644
--- a/common/Types.hs
+++ b/common/Types.hs
@@ -19,7 +19,7 @@ with this program.  If not, see <http://www.gnu.org/licenses/>.
 -- | Type inference and checking.
 module Types
   (
-    specTypeOfName, typeOfSpec, typeOfSpec', abbrevModeOfName, underlyingType, stripArrayType, abbrevModeOfVariable, abbrevModeOfSpec
+    specTypeOfName, typeOfSpec, typeOfSpec', abbrevModeOfName, underlyingType, underlyingTypeOf, stripArrayType, abbrevModeOfVariable, abbrevModeOfSpec
     , isRealType, isIntegerType, isNumericType, isCaseableType, isScalarType, isDataType, isCommunicableType, isSequenceType, isMobileType
     , resolveUserType, isSafeConversion, isPreciseConversion, isImplicitConversionRain
     , isOperator, functionOperator, occamDefaultOperator, occamBuiltInOperatorFunctions
@@ -64,6 +64,9 @@ class ASTTypeable a where
 instance ASTTypeable A.Type where
   astTypeOf = return
 
+underlyingTypeOf :: (ASTTypeable a, CSMR m, Die m) => Meta -> a -> m A.Type
+underlyingTypeOf m = underlyingType m <.< astTypeOf
+
 -- | Gets the 'A.AbbrevMode' for a given 'A.Name' from the recorded types in the 'CompState'.  Dies with an error if the name is unknown.
 abbrevModeOfName :: (CSMR m, Die m) => A.Name -> m A.AbbrevMode
 abbrevModeOfName n
diff --git a/frontends/OccamTypes.hs b/frontends/OccamTypes.hs
index 0f36d1e..5b78d58 100644
--- a/frontends/OccamTypes.hs
+++ b/frontends/OccamTypes.hs
@@ -721,7 +721,7 @@ inferTypes = occamOnlyPass "Infer types"
                          n -> show n ++ "-ary"
 
               es' <- noTypeContext $ mapM recurse es
-              tes <- sequence [astTypeOf e `catchError` (const $ return A.Infer) | e <- es']
+              tes <- sequence [underlyingTypeOf m e `catchError` (const $ return A.Infer) | e <- es']
            
               cs <- getCompState