diff --git a/src/Network/network_types.c b/src/Network/network_types.c
index 82f2c12..fe173b9 100644
--- a/src/Network/network_types.c
+++ b/src/Network/network_types.c
@@ -71,13 +71,16 @@ Maybe knIPV4Endpoint_fromStr(char* endStr, knIPV4Endpoint* endVal){
     i32 sep_i = cptr_seekChar(endStr, ':', 0, 48);
     if(sep_i < 7)
         safethrow(cptr_concat("can't find ':' in '", endStr, "'"), ;);
-    char* portBegin = endStr+sep_i+1;
+    const char* portBegin = endStr+sep_i+1;
     u64 port = knPort_INVALID;
     if(sscanf(portBegin, IFWIN("%llu", "%lu"), &port)!=1)
         safethrow(cptr_concat("can't recognise port number in '", portBegin, "'"), ;)
     
     knIPV4Address addr = knIPV4Address_INVALID;
-    try(knIPV4Address_fromStr(endStr, &addr), _m865, ;);
+    char* addrStr = cptr_copy(endStr);
+    addrStr[sep_i] = 0; 
+    try(knIPV4Address_fromStr(addrStr, &addr), _m865, ;);
+    free(addrStr);
 
     *endVal = knIPV4Endpoint_create(addr, port);
     return MaybeNull;
diff --git a/src/Network/network_types.h b/src/Network/network_types.h
index f167ddd..24d228a 100644
--- a/src/Network/network_types.h
+++ b/src/Network/network_types.h
@@ -23,7 +23,7 @@ kt_declare(knIPV4Address);
 #define knIPV4Address_ANY      knIPV4Address_fromBytes(0,0,0,0)
 #define knIPV4Address_LOOPBACK knIPV4Address_fromBytes(127,0,0,1)
 #define knIPV4Address_INVALID  knIPV4Address_fromBytes(255,255,255,255)
-#define knIPV4Address_isINVALID(ADDR) (ADDR.UintBigEndian == ~0)
+#define knIPV4Address_isINVALID(ADDR) (ADDR.UintBigEndian == (u32)~0)
 
 ///@return Maybe<null>
 Maybe knIPV4Address_fromStr(char* addrStr, knIPV4Address* addrPtr);