diff --git a/rtl/inc/generic.inc b/rtl/inc/generic.inc
index 4ded841654..d8af3fac1f 100644
--- a/rtl/inc/generic.inc
+++ b/rtl/inc/generic.inc
@@ -358,7 +358,7 @@ begin
   if (len < 0) or
      (len > high(PtrInt) div 2) or
      (psrc+len < psrc) then
-    pend:=pdword(high(PtrUInt)-sizeof(dword))
+    pend:=pdword(high(PtrUInt)-PtrUInt(sizeof(dword)))
   else
     pend:=psrc+len;
 {$ifdef FPC_REQUIRES_PROPER_ALIGNMENT}
@@ -399,7 +399,7 @@ begin
   if (len < 0) or
      (len > high(PtrInt) div 4) or
      (psrc+len < psrc) then
-    pend:=pqword(high(PtrUInt)-sizeof(qword))
+    pend:=pqword(high(PtrUInt)-PtrUInt(sizeof(qword)))
   else
     pend:=psrc+len;
 {$ifdef FPC_REQUIRES_PROPER_ALIGNMENT}
@@ -548,8 +548,7 @@ begin
           inc(pptruint(psrc));
         end;
     end;
-  if (len <= high(ptrint)) and
-     (psrc+len >= psrc) then
+  if (psrc+len >= psrc) then
     pend:=psrc+len
   else
     pend:=pword(high(ptruint)-2);
@@ -689,7 +688,7 @@ begin
   { simulate assembler implementations behaviour, which is expected }
   { fpc_pchar_to_ansistr in astrings.inc                            }
   if (len < 0) then
-    pend:=pbyte(high(PtrUInt)-sizeof(byte))
+    pend:=pbyte(high(PtrUInt)-PtrUInt(sizeof(byte)))
   else
     pend:=psrc+len;
   while (psrc<pend) and (psrc^<>0) do
diff --git a/rtl/inc/genmath.inc b/rtl/inc/genmath.inc
index ff07f35c90..90f385adf9 100644
--- a/rtl/inc/genmath.inc
+++ b/rtl/inc/genmath.inc
@@ -224,7 +224,7 @@ type
 invalid:
            float_raise(float_flag_invalid);
            if (aSign <> 0) then
-             float64_to_int32_round_to_zero:=$80000000
+             float64_to_int32_round_to_zero:=longint($80000000)
            else
              float64_to_int32_round_to_zero:=$7FFFFFFF;
            exit;
@@ -333,7 +333,7 @@ invalid:
                    exit;
                  end;
              End;
-           float32_to_int32_round_to_zero:=$80000000;
+           float32_to_int32_round_to_zero:=longint($80000000);
            exit;
          End
        else
diff --git a/rtl/win64/seh64.inc b/rtl/win64/seh64.inc
index c25e7cfbeb..c4411d6b44 100644
--- a/rtl/win64/seh64.inc
+++ b/rtl/win64/seh64.inc
@@ -304,6 +304,7 @@ begin
   args[1]:=PtrUint(Obj);
   args[2]:=GetBacktrace(ctx,AFrame,PPointer(args[3]));
   RaiseException(FPC_EXCEPTION_CODE,EXCEPTION_NONCONTINUABLE,4,@args[0]);
+  result:=nil;
 end;
 
 procedure _fpc_local_unwind(frame,target: Pointer);[public,alias:'_FPC_local_unwind'];compilerproc;
@@ -429,7 +430,7 @@ var
 begin
   Adr:=rec.ExceptionInformation[0];
   Obj:=TObject(rec.ExceptionInformation[1]);
-  Framecount:=Longint(rec.ExceptionInformation[2]);
+  Framecount:=Longint(PtrUInt(rec.ExceptionInformation[2]));
   Frames:=rec.ExceptionInformation[3];
 
   if rec.ExceptionCode<>FPC_EXCEPTION_CODE then
diff --git a/rtl/x86_64/x86_64.inc b/rtl/x86_64/x86_64.inc
index cfa0f5dfde..d75e2383db 100644
--- a/rtl/x86_64/x86_64.inc
+++ b/rtl/x86_64/x86_64.inc
@@ -673,9 +673,9 @@ function declocked(var l : longint) : boolean;assembler; nostackframe;
      { of time!                                             }
 {$ifdef FPC_PIC}
      movq       IsMultithread@GOTPCREL(%rip),%rax
-     cmpb       $0,(%rax)
+     cmpl       $0,(%rax)
 {$else FPC_PIC}
-     cmpb       $0,IsMultithread(%rip)
+     cmpl       $0,IsMultithread(%rip)
 {$endif FPC_PIC}
 {$ifndef win64}
      mov        %rdi, %rcx
@@ -698,9 +698,9 @@ function declocked(var l : int64) : boolean;assembler; nostackframe;
      { of time!                                             }
 {$ifdef FPC_PIC}
      movq       IsMultithread@GOTPCREL(%rip),%rax
-     cmpb       $0,(%rax)
+     cmpl       $0,(%rax)
 {$else FPC_PIC}
-     cmpb       $0,IsMultithread(%rip)
+     cmpl       $0,IsMultithread(%rip)
 {$endif FPC_PIC}
 {$ifndef win64}
      mov        %rdi, %rcx
@@ -724,9 +724,9 @@ procedure inclocked(var l : longint);assembler; nostackframe;
      { of time!                                             }
 {$ifdef FPC_PIC}
      movq       IsMultithread@GOTPCREL(%rip),%rax
-     cmpb       $0,(%rax)
+     cmpl       $0,(%rax)
 {$else FPC_PIC}
-     cmpb       $0,IsMultithread(%rip)
+     cmpl       $0,IsMultithread(%rip)
 {$endif FPC_PIC}
 {$ifndef win64}
      mov        %rdi, %rcx
@@ -749,9 +749,9 @@ procedure inclocked(var l : int64);assembler; nostackframe;
      { of time!                                             }
 {$ifdef FPC_PIC}
      movq       IsMultithread@GOTPCREL(%rip),%rax
-     cmpb       $0,(%rax)
+     cmpl       $0,(%rax)
 {$else FPC_PIC}
-     cmpb       $0,IsMultithread(%rip)
+     cmpl       $0,IsMultithread(%rip)
 {$endif FPC_PIC}
 {$ifndef win64}
      mov        %rdi, %rcx