diff --git a/src/dos/dos_execute.cpp b/src/dos/dos_execute.cpp
index b582a37e..80020c12 100644
--- a/src/dos/dos_execute.cpp
+++ b/src/dos/dos_execute.cpp
@@ -191,28 +191,24 @@ static void SetupPSP(Bit16u pspseg,Bit16u memsize,Bit16u envseg) {
 	dos.dta=RealMake(pspseg,0x80);
 }
 
-static void SetupCMDLine(Bit16u pspseg,ParamBlock * block) 
+static void SetupCMDLine(Bit16u pspseg,DOS_ParamBlock & block) 
 {
 	DOS_PSP psp(pspseg);
 	// if cmdtail==0 it will inited as empty in SetCommandTail
-	psp.SetCommandTail(block->exec.cmdtail);
+	psp.SetCommandTail(block.data.exec.cmdtail);
 }
 
-bool DOS_Execute(char * name,ParamBlock * _block,Bit8u flags) {
+bool DOS_Execute(char * name,PhysPt block_pt,Bit8u flags) {
 	EXE_Header head;Bitu i;
 	Bit16u fhandle;Bit16u len;Bit32u pos;
 	Bit16u pspseg,envseg,loadseg,memsize,readsize;
 	HostPt loadaddress;RealPt relocpt;
-	
 	Bitu headersize,imagesize;
+	DOS_ParamBlock block(block_pt);
+	block.LoadData();
 	if (flags!=LOADNGO && flags!=OVERLAY) {
 		E_Exit("DOS:Not supported execute mode %d for file %s",flags,name); 	
 	}
-	
-	// Parameter block may be overwritten on load, so save these values !
-	ParamBlock block;
-	memcpy(&block,_block,sizeof(ParamBlock));
-
 	/* Check for EXE or COM File */
 	bool iscom=false;
 	if (!DOS_OpenFile(name,OPEN_READ,&fhandle)) return false;
@@ -221,15 +217,22 @@ bool DOS_Execute(char * name,ParamBlock * _block,Bit8u flags) {
 		DOS_CloseFile(fhandle);
 		return false;
 	}
+	/* Convert the header to correct endian, i hope this works */
+	HostPt endian=(HostPt)&head;
+	for (i=0;i<sizeof(EXE_Header)/2;i++) {
+		*((Bit16u *)endian)=readw(endian);
+		endian+=2;
+	}
 	if (len<sizeof(EXE_Header)) iscom=true;	
 	if ((head.signature!=MAGIC1) && (head.signature!=MAGIC2)) iscom=true;
 	else {
 		headersize=head.headersize*16;
-		imagesize=(head.pages-1)*512-headersize+head.extrabytes;
+		imagesize=(head.pages)*512-headersize; 
+		if (head.extrabytes) imagesize-=(512-head.extrabytes);
 	}
 	if (flags!=OVERLAY) {
 		/* Create an environment block */
-		envseg=block.exec.envseg;
+		envseg=block.data.exec.envseg;
 		if (!MakeEnv(name,&envseg)) {
 			DOS_CloseFile(fhandle);
 			return false;
@@ -254,8 +257,8 @@ bool DOS_Execute(char * name,ParamBlock * _block,Bit8u flags) {
 		loadseg=pspseg+16;
 		/* Setup a psp */
 		SetupPSP(pspseg,memsize,envseg);
-		SetupCMDLine(pspseg,&block);
-	} else loadseg=block.overlay.loadseg,0;
+		SetupCMDLine(pspseg,block);
+	} else loadseg=block.data.overlay.loadseg;
 	/* Load the executable */
 	loadaddress=HostMake(loadseg,0);
 	if (iscom) {	/* COM Load 64k - 256 bytes max */
@@ -275,7 +278,7 @@ bool DOS_Execute(char * name,ParamBlock * _block,Bit8u flags) {
 		}
 		/* Relocate the exe image */
 		Bit16u relocate;
-		if (flags==OVERLAY) relocate=block.overlay.relocation;
+		if (flags==OVERLAY) relocate=block.data.overlay.relocation;
 		else relocate=loadseg;
 		pos=head.reloctable;DOS_SeekFile(fhandle,&pos,0);
 		for (i=0;i<head.relocations;i++) {
@@ -311,8 +314,8 @@ bool DOS_Execute(char * name,ParamBlock * _block,Bit8u flags) {
 		/* save vectors */
 		newpsp.SaveVectors();
 		/* copy fcbs */
-		newpsp.SetFCB1(block.exec.fcb1);
-		newpsp.SetFCB2(block.exec.fcb2);
+		newpsp.SetFCB1(block.data.exec.fcb1);
+		newpsp.SetFCB2(block.data.exec.fcb2);
 		/* Set the stack for new program */
 		SegSet16(ss,RealSeg(sssp));reg_sp=RealOff(sssp);
 		/* Add some flags and CS:IP on the stack for the IRET */