diff --git a/src/sparsevec.h b/src/sparsevec.h
index ef4041b..75625c1 100644
--- a/src/sparsevec.h
+++ b/src/sparsevec.h
@@ -6,22 +6,35 @@
 #define SPARSEVEC_MAX_DIM 1000000
 #define SPARSEVEC_MAX_NNZ 16000
 
-/* Ensure values are aligned */
-#define SPARSEVEC_SIZE(_nnz)		(offsetof(SparseVector, indices) + MAXALIGN((_nnz) * sizeof(int32)) + (_nnz * sizeof(float)))
-#define SPARSEVEC_VALUES(x)		((float *) (((char *) (x)) + offsetof(SparseVector, indices) + MAXALIGN((x)->nnz * sizeof(int32))))
 #define DatumGetSparseVector(x)		((SparseVector *) PG_DETOAST_DATUM(x))
 #define PG_GETARG_SPARSEVEC_P(x)	DatumGetSparseVector(PG_GETARG_DATUM(x))
 #define PG_RETURN_SPARSEVEC_P(x)	PG_RETURN_POINTER(x)
 
+/* Indices are always sorted */
+/* Values come after indices */
 typedef struct SparseVector
 {
 	int32		vl_len_;		/* varlena header (do not touch directly!) */
 	int32		dim;			/* number of dimensions */
-	int32		nnz;
+	int32		nnz;			/* number of non-zero elements */
 	int32		unused;
 	int32		indices[FLEXIBLE_ARRAY_MEMBER];
 }			SparseVector;
 
+/* Use functions instead of macros to avoid double evaluation */
+
+static inline Size
+SPARSEVEC_SIZE(int nnz)
+{
+	return offsetof(SparseVector, indices) + (nnz * sizeof(int32)) + (nnz * sizeof(float));
+}
+
+static inline float *
+SPARSEVEC_VALUES(SparseVector * x)
+{
+	return (float *) (((char *) x) + offsetof(SparseVector, indices) + (x->nnz * sizeof(int32)));
+}
+
 SparseVector *InitSparseVector(int dim, int nnz);
 
 #endif