diff --git a/include/tins/ip.h b/include/tins/ip.h
index 773acf6..c33029e 100644
--- a/include/tins/ip.h
+++ b/include/tins/ip.h
@@ -329,7 +329,7 @@ namespace Tins {
          * \return The IP flags field
          */
         Flags flags() const {
-            return static_cast<Flags>((_ip.frag_off & 0xe0) >> 5); 
+            return static_cast<Flags>(Endian::be_to_host(_ip.frag_off) >> 13); 
         }
 
         /**
diff --git a/src/ip.cpp b/src/ip.cpp
index e9af2ff..2a8d4c9 100644
--- a/src/ip.cpp
+++ b/src/ip.cpp
@@ -179,11 +179,13 @@ void IP::frag_off(uint16_t new_frag_off) {
 }
 
 void IP::fragment_offset(small_uint<13> new_frag_off) {
-    _ip.frag_off = (_ip.frag_off & 0xe0) | Endian::host_to_be<uint16_t>(new_frag_off);
+    uint16_t value = (Endian::be_to_host(_ip.frag_off) & 0xe000) | new_frag_off;
+    _ip.frag_off = Endian::host_to_be(value);
 }
 
 void IP::flags(Flags new_flags) {
-    _ip.frag_off = (_ip.frag_off & 0xff1f) | (new_flags << 5);
+    uint16_t value = (Endian::be_to_host(_ip.frag_off) & 0x1fff) | (new_flags << 13);
+    _ip.frag_off = Endian::host_to_be(value);
 }
 
 void IP::ttl(uint8_t new_ttl) {
diff --git a/src/ip_reassembler.cpp b/src/ip_reassembler.cpp
index afb80e5..1cb3cbf 100644
--- a/src/ip_reassembler.cpp
+++ b/src/ip_reassembler.cpp
@@ -112,7 +112,8 @@ IPv4Reassembler::packet_status IPv4Reassembler::process(PDU &pdu) {
                     return FRAGMENTED;
                 }
                 ip->inner_pdu(pdu);
-                ip->frag_off(0);
+                ip->fragment_offset(0);
+                ip->flags(static_cast<IP::Flags>(0));
                 return REASSEMBLED;
             }
             else