diff --git a/src/state.cpp b/src/state.cpp
index 75de75ac..90871905 100644
--- a/src/state.cpp
+++ b/src/state.cpp
@@ -133,7 +133,7 @@ static int SubWrite(EMUFILE* os, SFORMAT *sf)
 
 	while(sf->v)
 	{
-		if(sf->s==~0)		//Link to another struct
+		if(sf->s==~0u)		//Link to another struct
 		{
 			uint32 tmp;
 
@@ -191,7 +191,7 @@ static SFORMAT *CheckS(SFORMAT *sf, uint32 tsize, char *desc)
 {
 	while(sf->v)
 	{
-		if(sf->s==~0)		// Link to another SFORMAT structure.
+		if(sf->s==~0u)		// Link to another SFORMAT structure.
 		{
 			SFORMAT *tmp;
 			if((tmp= CheckS((SFORMAT *)sf->v, tsize, desc) ))
@@ -427,7 +427,7 @@ bool FCEUSS_SaveMS(EMUFILE* outstream, int compressionLevel)
 	if(SPostSave) SPostSave();
 
 	//save the length of the file
-	int len = memory_savestate.size();
+	size_t len = memory_savestate.size();
 
 	//sanity check: len and totalsize should be the same
 	if(len != totalsize)
@@ -438,7 +438,7 @@ bool FCEUSS_SaveMS(EMUFILE* outstream, int compressionLevel)
 
 	int error = Z_OK;
 	uint8* cbuf = (uint8*)memory_savestate.buf();
-	uLongf comprlen = -1;
+	uLongf comprlen = ~0lu;
 	if(compressionLevel != Z_NO_COMPRESSION && (compressSavestates || FCEUMOV_Mode(MOVIEMODE_TASEDITOR)))
 	{
 		// worst case compression: zlib says "0.1% larger than sourceLen plus 12 bytes"
@@ -457,7 +457,7 @@ bool FCEUSS_SaveMS(EMUFILE* outstream, int compressionLevel)
 
 	//dump it to the destination file
 	outstream->fwrite((char*)header,16);
-	outstream->fwrite((char*)cbuf,comprlen==-1?totalsize:comprlen);
+	outstream->fwrite((char*)cbuf,comprlen==~0lu?totalsize:comprlen);
 
 	return error == Z_OK;
 }
@@ -666,22 +666,22 @@ bool FCEUSS_LoadFP(EMUFILE* is, ENUM_SSLOADPARAMS params)
 		return ret;
 	}
 
-	int totalsize = FCEU_de32lsb(header + 4);
-	int stateversion = FCEU_de32lsb(header + 8);
-	int comprlen = FCEU_de32lsb(header + 12);
+	size_t totalsize  = FCEU_de32lsb(header + 4);
+	int stateversion  = FCEU_de32lsb(header + 8);
+	uint32_t comprlen = FCEU_de32lsb(header + 12);
 
 	// reinit memory_savestate
 	// memory_savestate is global variable which already has its vector of bytes, so no need to allocate memory every time we use save/loadstate
-	if ((int)(memory_savestate.get_vec())->size() < totalsize)
+	if ((memory_savestate.get_vec())->size() < totalsize)
 		(memory_savestate.get_vec())->resize(totalsize);
 	memory_savestate.set_len(totalsize);
 	memory_savestate.unfail();
 	memory_savestate.fseek(0, SEEK_SET);
 
-	if(comprlen != -1)
+	if(comprlen != ~0u)
 	{
 		// the savestate is compressed: read from is to compressed_buf, then decompress from compressed_buf to memory_savestate.vec
-		if ((int)compressed_buf.size() < comprlen) compressed_buf.resize(comprlen);
+		if (compressed_buf.size() < comprlen) compressed_buf.resize(comprlen);
 		is->fread(&compressed_buf[0], comprlen);
 
 		uLongf uncomprlen = totalsize;
@@ -874,7 +874,7 @@ void AddExState(void *v, uint32 s, int type, const char *desc)
 	//do not accept extra state information if a null pointer was provided for v, so list won't terminate early
 	if (v == 0) return;
 	
-	if(s==~0)
+	if(s==~0u)
 	{
 		SFORMAT* sf = (SFORMAT*)v;
 		std::map<std::string,bool> names;