diff --git a/infrastructure-centred/owlps-client/owlps-client.c b/infrastructure-centred/owlps-client/owlps-client.c
index 1622c69..39c5a49 100644
--- a/infrastructure-centred/owlps-client/owlps-client.c
+++ b/infrastructure-centred/owlps-client/owlps-client.c
@@ -296,10 +296,11 @@ void make_packet()
 
       offset = 0 ;
       packet_size =
-        sizeof(char) * 2 + sizeof(TIMESTAMP) + sizeof(float) * 3 ;
+        sizeof(uint8_t) * 2 + sizeof(TIMESTAMP) + sizeof(float) * 3 ;
       packet = malloc(packet_size) ;
 
-      packet[offset++] = PACKET_TYPE_CALIBRATION ; // Packet type
+      memset(&packet[offset], PACKET_TYPE_CALIBRATION, 1) ; // Packet type
+      ++offset ;
       memcpy(&packet[offset], &request_time, sizeof(request_time)) ;
       offset += sizeof(request_time) ;
       packet[offset++] = options.direction ; // Direction
@@ -318,9 +319,9 @@ void make_packet()
     {
       printf("Request time: %"PRIu64"\n",
              timestamp_to_ms(request_time)) ;
-      packet_size = sizeof(char) + sizeof(TIMESTAMP) ;
+      packet_size = sizeof(uint8_t) + sizeof(TIMESTAMP) ;
       packet = malloc(packet_size) ;
-      packet[0] = PACKET_TYPE_NORMAL ; // Packet type
+      memset(&packet[0], PACKET_TYPE_NORMAL, 1) ; // Packet type
       memcpy(&packet[1], &request_time, sizeof(request_time)) ;
     }
 }