diff --git a/rtl/inc/genmath.inc b/rtl/inc/genmath.inc
index fa0aa0dc35..d505164747 100644
--- a/rtl/inc/genmath.inc
+++ b/rtl/inc/genmath.inc
@@ -676,17 +676,17 @@ type
      * to produce the hexadecimal values shown.
      *
     }
-    function fpc_exp_real(x: Double):Double;compilerproc;
+    function fpc_exp_real(d: Double):Double;compilerproc;
       const
-        one   = 1.0,
+        one   = 1.0;
         halF : array[0..1] of double = (0.5,-0.5);
         huge	= 1.0e+300;
         twom1000 = 9.33263618503218878990e-302;     { 2**-1000=0x01700000,0}
         o_threshold =  7.09782712893383973096e+02;  { 0x40862E42, 0xFEFA39EF }
         u_threshold = -7.45133219101941108420e+02;  { 0xc0874910, 0xD52D3051 }
-        ln2HI  : array[0..1] of double = ( 6.93147180369123816490e-01:  { 0x3fe62e42, 0xfee00000 }
+        ln2HI  : array[0..1] of double = ( 6.93147180369123816490e-01,  { 0x3fe62e42, 0xfee00000 }
              -6.93147180369123816490e-01); { 0xbfe62e42, 0xfee00000 }
-        ln2LO : array[0..1] of double = (1.90821492927058770002e-10;  { 0x3dea39ef, 0x35793c76 }
+        ln2LO : array[0..1] of double = (1.90821492927058770002e-10,  { 0x3dea39ef, 0x35793c76 }
              -1.90821492927058770002e-10); { 0xbdea39ef, 0x35793c76 }
         invln2 =  1.44269504088896338700e+00; { 0x3ff71547, 0x652b82fe }
         P1   =  1.66666666666666019037e-01; { 0x3FC55555, 0x5555553E }
@@ -695,44 +695,43 @@ type
         P4   = -1.65339022054652515390e-06; { 0xBEBBBD41, 0xC5D26BF1 }
         P5   =  4.13813679705723846039e-08; { 0x3E663769, 0x72BEA4D0 }
       var
-        double hi : double = 0.0;
-	double lo = 0.0;
-	c : double;
-	t : double;
-	int32_t k=0;
-	xsb : longint;
+	c,hi,lo,t,y : double;
+	k,xsb : longint;
 	hx,hy,lx : dword;
       begin
-        hx:=float64(x).high;
-        xsb := (hx shr 31) and 1;               { sign bit of x }
-        hx := hx and $7fffffff;                 { high word of |x| }
+        hi:=0.0;
+        lo:=0.0;
+        k:=0;
+        hx:=float64(d).high;
+        xsb := (hx shr 31) and 1;               { sign bit of d }
+        hx := hx and $7fffffff;                 { high word of |d| }
 
         { filter out non-finite argument }
         if hx >= $40862E42 then
-          begin                  { if |x|>=709.78... }
-            if hx >= $7ff00000
+          begin                  { if |d|>=709.78... }
+            if hx >= $7ff00000 then
               begin
-                lx:=float64(x).low;
+                lx:=float64(d).low;
                 if ((hx and $fffff) or lx)<>0 then
                   begin
-                    result:=x+x; { NaN }
+                    result:=d+d; { NaN }
                     exit;
-                  else
+                  end
                 else
                   begin
                     if xsb=0 then
-                      result:=x
+                      result:=d
                     else
                       result:=0.0;    { exp(+-inf)=begininf,0end }
                     exit;
                   end;
               end;
-            if x > o_threshold then
+            if d > o_threshold then
               begin
                 result:=huge*huge; { overflow }
                 exit;
               end;
-            if x < u_threshold then
+            if d < u_threshold then
               begin
                 result:=twom1000*twom1000; { underflow }
                 exit;
@@ -741,45 +740,45 @@ type
 
         { argument reduction }
         if hx > $3fd62e42 then
-          begin           { if  |x| > 0.5 ln2 }
-            if hx < $3FF0A2B2 then { and |x| < 1.5 ln2 }
+          begin           { if  |d| > 0.5 ln2 }
+            if hx < $3FF0A2B2 then { and |d| < 1.5 ln2 }
               begin
-                hi := x-ln2HI[xsb];
+                hi := d-ln2HI[xsb];
                 lo:=ln2LO[xsb];
                 k := 1-xsb-xsb;
               end
             else
               begin
-		k  := invln2*x+halF[xsb];
+		k  := round(invln2*d+halF[xsb]);
 		t  := k;
-                hi := x - t*ln2HI[0];    { t*ln2HI is exact here }
+                hi := d - t*ln2HI[0];    { t*ln2HI is exact here }
 		lo := t*ln2LO[0];
               end;
-            x  := hi - lo;
+            d  := hi - lo;
           end
         else if hx < $3e300000 then
-          begin     { when |x|<2**-28 }
-            if huge+x>one then
+          begin     { when |d|<2**-28 }
+            if huge+d>one then
               begin
-                result:=one+x;{ trigger inexact }
+                result:=one+d;{ trigger inexact }
                 exit;
               end;
           end
 	else
           k := 0;
 
-        { x is now in primary range }
-	t:=x*x;
-	c:=x - t*(P1+t*(P2+t*(P3+t*(P4+t*P5))));
+        { d is now in primary range }
+	t:=d*d;
+	c:=d - t*(P1+t*(P2+t*(P3+t*(P4+t*P5))));
 	if k=0 then
           begin
-            result:=one-((x*c)/(c-2.0)-x);
+            result:=one-((d*c)/(c-2.0)-d);
             exit;
           end
 	else
-          y := one-((lo-(x*c)/(2.0-c))-hi);
+          y := one-((lo-(d*c)/(2.0-c))-hi);
 
-        if k >= -1021
+        if k >= -1021 then
           begin
             hy:=float64(y).high;
             float64(y).high:=hy+(k shl 20);        { add k to y's exponent }