diff --git a/sql/vector--0.4.4--0.5.0.sql b/sql/vector--0.4.4--0.5.0.sql
index 1521589..3fe3365 100644
--- a/sql/vector--0.4.4--0.5.0.sql
+++ b/sql/vector--0.4.4--0.5.0.sql
@@ -12,14 +12,9 @@ CREATE OPERATOR * (
 	COMMUTATOR = *
 );
 
-CREATE FUNCTION vector_sum(double precision[]) RETURNS vector
-	AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;
-
 CREATE AGGREGATE sum(vector) (
-	SFUNC = vector_accum,
-	STYPE = double precision[],
-	FINALFUNC = vector_sum,
-	COMBINEFUNC = vector_combine,
-	INITCOND = '{0}',
+	SFUNC = vector_add,
+	STYPE = vector,
+	COMBINEFUNC = vector_add,
 	PARALLEL = SAFE
 );
diff --git a/sql/vector.sql b/sql/vector.sql
index 55f830b..91f594c 100644
--- a/sql/vector.sql
+++ b/sql/vector.sql
@@ -99,9 +99,6 @@ CREATE FUNCTION vector_avg(double precision[]) RETURNS vector
 CREATE FUNCTION vector_combine(double precision[], double precision[]) RETURNS double precision[]
 	AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;
 
-CREATE FUNCTION vector_sum(double precision[]) RETURNS vector
-	AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;
-
 -- aggregates
 
 CREATE AGGREGATE avg(vector) (
@@ -114,11 +111,9 @@ CREATE AGGREGATE avg(vector) (
 );
 
 CREATE AGGREGATE sum(vector) (
-	SFUNC = vector_accum,
-	STYPE = double precision[],
-	FINALFUNC = vector_sum,
-	COMBINEFUNC = vector_combine,
-	INITCOND = '{0}',
+	SFUNC = vector_add,
+	STYPE = vector,
+	COMBINEFUNC = vector_add,
 	PARALLEL = SAFE
 );
 
diff --git a/src/vector.c b/src/vector.c
index 5cecf7e..e9a151e 100644
--- a/src/vector.c
+++ b/src/vector.c
@@ -1090,42 +1090,3 @@ vector_avg(PG_FUNCTION_ARGS)
 
 	PG_RETURN_POINTER(result);
 }
-
-/*
- * Sum vectors
- */
-PGDLLEXPORT PG_FUNCTION_INFO_V1(vector_sum);
-Datum
-vector_sum(PG_FUNCTION_ARGS)
-{
-	ArrayType  *statearray = PG_GETARG_ARRAYTYPE_P(0);
-	float8	   *statevalues;
-	float8		n;
-	uint16		dim;
-	Vector	   *result;
-
-	/* Check array before using */
-	statevalues = CheckStateArray(statearray, "vector_sum");
-	n = statevalues[0];
-
-	/* SQL defines AVG of no values to be NULL */
-	if (n == 0.0)
-		PG_RETURN_NULL();
-
-	/* Create vector */
-	dim = STATE_DIMS(statearray);
-	CheckDim(dim);
-	result = InitVector(dim);
-	for (int i = 0; i < dim; i++)
-	{
-		result->x[i] = statevalues[i + 1];
-
-		/* Check for overflow */
-		if (isinf(result->x[i]))
-			float_overflow_error();
-
-		CheckElement(result->x[i]);
-	}
-
-	PG_RETURN_POINTER(result);
-}
diff --git a/test/expected/functions.out b/test/expected/functions.out
index 86562b2..46bb8fe 100644
--- a/test/expected/functions.out
+++ b/test/expected/functions.out
@@ -157,8 +157,6 @@ SELECT sum(v) FROM unnest(ARRAY[]::vector[]) v;
 (1 row)
 
 SELECT sum(v) FROM unnest(ARRAY['[1,2]'::vector, '[3]']) v;
-ERROR:  expected 2 dimensions, not 1
+ERROR:  different vector dimensions 2 and 1
 SELECT sum(v) FROM unnest(ARRAY['[3e38]'::vector, '[3e38]']) v;
 ERROR:  value out of range: overflow
-SELECT vector_sum(array_agg(n)) FROM generate_series(1, 16002) n;
-ERROR:  vector cannot have more than 16000 dimensions
diff --git a/test/sql/functions.sql b/test/sql/functions.sql
index e1c5a42..fa29717 100644
--- a/test/sql/functions.sql
+++ b/test/sql/functions.sql
@@ -41,4 +41,3 @@ SELECT sum(v) FROM unnest(ARRAY['[1,2,3]'::vector, '[3,5,7]', NULL]) v;
 SELECT sum(v) FROM unnest(ARRAY[]::vector[]) v;
 SELECT sum(v) FROM unnest(ARRAY['[1,2]'::vector, '[3]']) v;
 SELECT sum(v) FROM unnest(ARRAY['[3e38]'::vector, '[3e38]']) v;
-SELECT vector_sum(array_agg(n)) FROM generate_series(1, 16002) n;