diff --git a/src/sparsevec.c b/src/sparsevec.c
index 270b049..2d41214 100644
--- a/src/sparsevec.c
+++ b/src/sparsevec.c
@@ -943,10 +943,10 @@ sparsevec_cmp_internal(SparseVector * a, SparseVector * b)
 			return 1;
 	}
 
-	if (a->nnz < b->nnz)
+	if (a->nnz < b->nnz && b->indices[nnz] <= a->dim)
 		return bx[nnz] < 0 ? 1 : -1;
 
-	if (a->nnz > b->nnz)
+	if (a->nnz > b->nnz && a->indices[nnz] <= b->dim)
 		return ax[nnz] < 0 ? -1 : 1;
 
 	if (a->dim < b->dim)
diff --git a/test/t/033_comparison.pl b/test/t/033_comparison.pl
new file mode 100644
index 0000000..a30043b
--- /dev/null
+++ b/test/t/033_comparison.pl
@@ -0,0 +1,48 @@
+use strict;
+use warnings;
+use PostgresNode;
+use TestLib;
+use Test::More;
+
+my $node;
+my $array_sql = join(",", ('floor(random() * 2)::int - 1') x 3);
+
+# Initialize node
+$node = get_new_node('node');
+$node->init;
+$node->start;
+
+# Create table
+$node->safe_psql("postgres", "CREATE EXTENSION vector;");
+$node->safe_psql("postgres", "CREATE TABLE tst (v real[]);");
+$node->safe_psql("postgres",
+	"INSERT INTO tst SELECT ARRAY[$array_sql] FROM generate_series(1, 10000) i;"
+);
+
+for (1 .. 50)
+{
+	# Generate queries
+	my @r = ();
+	for (1 .. (int(rand() * 3) + 2))
+	{
+		push(@r, int(rand() * 2) - 1);
+	}
+	my $query = "{" . join(",", @r) . "}";
+
+	# Get expected results
+	my $expected = $node->safe_psql("postgres", "SELECT btarraycmp(v, '$query') FROM tst");
+
+	# Test vector
+	my $actual = $node->safe_psql("postgres", "SELECT vector_cmp(v::vector, '$query'::real[]::vector) FROM tst");
+	is($expected, $actual);
+
+	# Test halfvec
+	$actual = $node->safe_psql("postgres", "SELECT halfvec_cmp(v::halfvec, '$query'::real[]::halfvec) FROM tst");
+	is($expected, $actual);
+
+	# Test sparsevec
+	$actual = $node->safe_psql("postgres", "SELECT sparsevec_cmp(v::vector::sparsevec, '$query'::real[]::vector::sparsevec) FROM tst");
+	is($expected, $actual);
+}
+
+done_testing();