diff --git a/src/vector.c b/src/vector.c
index 7da2bf3..4c1f695 100644
--- a/src/vector.c
+++ b/src/vector.c
@@ -946,8 +946,18 @@ binary_quantize(PG_FUNCTION_ARGS)
 	float	   *ax = a->x;
 	VarBit	   *result = InitBitVector(a->dim);
 	unsigned char *rx = VARBITS(result);
+	int			i;
+	int			count = (a->dim / 8) * 8;
+	unsigned char result_byte;
 
-	for (int i = 0; i < a->dim; i++)
+	for (i = 0; i < count; i += 8)
+	{
+		result_byte = 0;
+		for (int j = 0; j < 8; j++)
+			result_byte |= (ax[i + j] > 0) << (7 - j);
+		rx[i / 8] = result_byte;
+	}
+	for (; i < a->dim; i++)
 		rx[i / 8] |= (ax[i] > 0) << (7 - (i % 8));
 
 	PG_RETURN_VARBIT_P(result);