diff --git a/src/backend/utils/adt/arrayfuncs.c b/src/backend/utils/adt/arrayfuncs.c
index 91df184..5e1d9c2 100644
--- a/src/backend/utils/adt/arrayfuncs.c
+++ b/src/backend/utils/adt/arrayfuncs.c
@@ -1719,11 +1719,15 @@ array_upper(PG_FUNCTION_ARGS)
 Datum
 array_length(PG_FUNCTION_ARGS)
 {
-	ArrayType  *v = PG_GETARG_ARRAYTYPE_P(0);
+	Datum		arrdatum = PG_GETARG_DATUM(0);
 	int			reqdim = PG_GETARG_INT32(1);
+	ArrayType  *v;
 	int		   *dimv;
 	int			result;
 
+	v = (ArrayType *) PG_DETOAST_DATUM_SLICE(arrdatum, 0,
+											 ARR_OVERHEAD_NONULLS(MAXDIM));
+
 	/* Sanity check: does it look like an array at all? */
 	if (ARR_NDIM(v) <= 0 || ARR_NDIM(v) > MAXDIM)
 		PG_RETURN_NULL();