diff --git a/Makefile b/Makefile
index 54acceb0..2dce0e01 100644
--- a/Makefile
+++ b/Makefile
@@ -1,6 +1,6 @@
 
 LDFLAGS=-lrt -lpcap -lsodium
-CPPFLAGS=-Wall -g
+CPPFLAGS=-Wall -O2
 
 all: rx tx keygen
 
diff --git a/tx.cpp b/tx.cpp
index d2c79ce4..efe18459 100644
--- a/tx.cpp
+++ b/tx.cpp
@@ -333,7 +333,7 @@ int main(int argc, char * const *argv)
             fprintf(stderr, "Usage: %s [-K tx_key] [-m mavlink_agg_in_ms] [-k RS_K] [-n RS_N] [-u udp_port] [-p radio_port] interface\n",
                     argv[0]);
             fprintf(stderr, "Default: K='%s', k=%d, n=%d, udp_port=%d, radio_port=%d\n", keypair.c_str(), k, n, udp_port, radio_port);
-            fprintf(stderr, "Radio MTU: %lu\n", MAX_PAYLOAD_SIZE);
+            fprintf(stderr, "Radio MTU: %lu\n", (unsigned long)MAX_PAYLOAD_SIZE);
             exit(1);
         }
     }
diff --git a/wifibroadcast.hpp b/wifibroadcast.hpp
index 941afb7b..1eb914a1 100644
--- a/wifibroadcast.hpp
+++ b/wifibroadcast.hpp
@@ -104,7 +104,7 @@ static uint8_t ieee80211_header[] = {
 
 // nonce:  56bit block_idx + 8bit fragment_idx
 
-#define BLOCK_IDX_MASK ((1LU << 56) - 1)
+#define BLOCK_IDX_MASK ((1LLU << 56) - 1)
 
 #define WFB_PACKET_DATA 0x1
 #define WFB_PACKET_KEY 0x2