diff --git a/jerry-libm/acos.c b/jerry-libm/acos.c
index d3b688df3..875d41ef5 100644
--- a/jerry-libm/acos.c
+++ b/jerry-libm/acos.c
@@ -70,7 +70,7 @@
 double
 acos (double x)
 {
-  double z, p, q, r, w, s, c, df;
+  double z, p, q, r, w, s, c;
   int hx, ix;
 
   hx = __HI (x);
@@ -114,16 +114,17 @@ acos (double x)
   }
   else /* x > 0.5 */
   {
+    double_accessor df;
     z = (one - x) * 0.5;
     s = sqrt (z);
-    df = s;
-    __LO (df) = 0;
-    c = (z - df * df) / (s + df);
+    df.dbl = s;
+    df.as_int.lo = 0;
+    c = (z - df.dbl * df.dbl) / (s + df.dbl);
     p = z * (pS0 + z * (pS1 + z * (pS2 + z * (pS3 + z * (pS4 + z * pS5)))));
     q = one + z * (qS1 + z * (qS2 + z * (qS3 + z * qS4)));
     r = p / q;
     w = r * s + c;
-    return 2.0 * (df + w);
+    return 2.0 * (df.dbl + w);
   }
 } /* acos */
 
diff --git a/jerry-libm/asin.c b/jerry-libm/asin.c
index 3db5e36cb..1af9c3c52 100644
--- a/jerry-libm/asin.c
+++ b/jerry-libm/asin.c
@@ -77,7 +77,8 @@
 double
 asin (double x)
 {
-  double t, w, p, q, c, r, s;
+  double t, p, q, c, r, s;
+  double_accessor w;
   int hx, ix;
 
   hx = __HI (x);
@@ -102,28 +103,28 @@ asin (double x)
     t = x * x;
     p = t * (pS0 + t * (pS1 + t * (pS2 + t * (pS3 + t * (pS4 + t * pS5)))));
     q = one + t * (qS1 + t * (qS2 + t * (qS3 + t * qS4)));
-    w = p / q;
-    return x + x * w;
+    w.dbl = p / q;
+    return x + x * w.dbl;
   }
   /* 1 > |x| >= 0.5 */
-  w = one - fabs (x);
-  t = w * 0.5;
+  w.dbl = one - fabs (x);
+  t = w.dbl * 0.5;
   p = t * (pS0 + t * (pS1 + t * (pS2 + t * (pS3 + t * (pS4 + t * pS5)))));
   q = one + t * (qS1 + t * (qS2 + t * (qS3 + t * qS4)));
   s = sqrt (t);
   if (ix >= 0x3FEF3333) /* if |x| > 0.975 */
   {
-    w = p / q;
-    t = pio2_hi - (2.0 * (s + s * w) - pio2_lo);
+    w.dbl = p / q;
+    t = pio2_hi - (2.0 * (s + s * w.dbl) - pio2_lo);
   }
   else
   {
-    w = s;
-    __LO (w) = 0;
-    c = (t - w * w) / (s + w);
+    w.dbl = s;
+    w.as_int.lo = 0;
+    c = (t - w.dbl * w.dbl) / (s + w.dbl);
     r = p / q;
     p = 2.0 * s * r - (pio2_lo - 2.0 * c);
-    q = pio4_hi - 2.0 * w;
+    q = pio4_hi - 2.0 * w.dbl;
     t = pio4_hi - (p - q);
   }
   if (hx > 0)
diff --git a/jerry-libm/atan2.c b/jerry-libm/atan2.c
index 47764153b..025e128f0 100644
--- a/jerry-libm/atan2.c
+++ b/jerry-libm/atan2.c
@@ -64,7 +64,7 @@
 double
 atan2 (double y, double x)
 {
-  double z;
+  double_accessor z;
   int k, m, hx, hy, ix, iy;
   unsigned lx, ly;
 
@@ -168,35 +168,35 @@ atan2 (double y, double x)
   k = (iy - ix) >> 20;
   if (k > 60) /* |y / x| > 2**60 */
   {
-    z = pi_o_2 + 0.5 * pi_lo;
+    z.dbl = pi_o_2 + 0.5 * pi_lo;
   }
   else if (hx < 0 && k < -60) /* |y| / x < -2**60 */
   {
-    z = 0.0;
+    z.dbl = 0.0;
   }
   else /* safe to do y / x */
   {
-    z = atan (fabs (y / x));
+    z.dbl = atan (fabs (y / x));
   }
   switch (m)
   {
     case 0: /* atan(+,+) */
     {
-      return z;
+      return z.dbl;
     }
     case 1: /* atan(-,+) */
     {
-      __HI (z) ^= 0x80000000;
-      return z;
+      z.as_int.hi ^= 0x80000000;
+      return z.dbl;
     }
     case 2: /* atan(+,-) */
     {
-      return pi - (z - pi_lo);
+      return pi - (z.dbl - pi_lo);
     }
     /* case 3: */
     default: /* atan(-,-) */
     {
-      return (z - pi_lo) - pi;
+      return (z.dbl - pi_lo) - pi;
     }
   }
 } /* atan2 */
diff --git a/jerry-libm/ceil.c b/jerry-libm/ceil.c
index fda9b2be2..578cb62c3 100644
--- a/jerry-libm/ceil.c
+++ b/jerry-libm/ceil.c
@@ -123,9 +123,11 @@ ceil (double x)
       i1 &= (~i);
     }
   }
-  __HI (x) = i0;
-  __LO (x) = i1;
-  return x;
+
+  double_accessor ret;
+  ret.as_int.hi = i0;
+  ret.as_int.lo = i1;
+  return ret.dbl;
 } /* ceil */
 
 #undef huge
diff --git a/jerry-libm/copysign.c b/jerry-libm/copysign.c
index 48d35f74d..23e209a49 100644
--- a/jerry-libm/copysign.c
+++ b/jerry-libm/copysign.c
@@ -34,6 +34,8 @@
 double
 copysign (double x, double y)
 {
-  __HI (x) = (__HI (x) & 0x7fffffff) | (__HI (y) & 0x80000000);
-  return x;
+  double_accessor ret;
+  ret.dbl = x;
+  ret.as_int.hi = (__HI (x) & 0x7fffffff) | (__HI (y) & 0x80000000);
+  return ret.dbl;
 } /* copysign */
diff --git a/jerry-libm/exp.c b/jerry-libm/exp.c
index f20d7d5d1..8970528fc 100644
--- a/jerry-libm/exp.c
+++ b/jerry-libm/exp.c
@@ -120,7 +120,7 @@ static const double ln2LO[2] =
 double
 exp (double x) /* default IEEE double exp */
 {
-  double y, hi, lo, c, t;
+  double hi, lo, c, t;
   int k = 0, xsb;
   unsigned hx;
 
@@ -182,6 +182,8 @@ exp (double x) /* default IEEE double exp */
     k = 0;
   }
 
+  double_accessor ret;
+
   /* x is now in primary range */
   t = x * x;
   c = x - t * (P1 + t * (P2 + t * (P3 + t * (P4 + t * P5))));
@@ -191,17 +193,17 @@ exp (double x) /* default IEEE double exp */
   }
   else
   {
-    y = one - ((lo - (x * c) / (2.0 - c)) - hi);
+    ret.dbl = one - ((lo - (x * c) / (2.0 - c)) - hi);
   }
   if (k >= -1021)
   {
-    __HI (y) += (k << 20); /* add k to y's exponent */
-    return y;
+    ret.as_int.hi += (k << 20); /* add k to y's exponent */
+    return ret.dbl;
   }
   else
   {
-    __HI (y) += ((k + 1000) << 20); /* add k to y's exponent */
-    return y * twom1000;
+    ret.as_int.hi += ((k + 1000) << 20); /* add k to y's exponent */
+    return ret.dbl * twom1000;
   }
 } /* exp */
 
diff --git a/jerry-libm/fabs.c b/jerry-libm/fabs.c
index ed208357f..6364d02a5 100644
--- a/jerry-libm/fabs.c
+++ b/jerry-libm/fabs.c
@@ -33,6 +33,8 @@
 double
 fabs (double x)
 {
-  __HI (x) &= 0x7fffffff;
-  return x;
+  double_accessor ret;
+  ret.dbl = x;
+  ret.as_int.hi &= 0x7fffffff;
+  return ret.dbl;
 } /* fabs */
diff --git a/jerry-libm/floor.c b/jerry-libm/floor.c
index b279cd0af..ade7921d8 100644
--- a/jerry-libm/floor.c
+++ b/jerry-libm/floor.c
@@ -122,9 +122,11 @@ floor (double x)
       i1 &= (~i);
     }
   }
-  __HI (x) = i0;
-  __LO (x) = i1;
-  return x;
+
+  double_accessor ret;
+  ret.as_int.hi = i0;
+  ret.as_int.lo = i1;
+  return ret.dbl;
 } /* floor */
 
 #undef huge
diff --git a/jerry-libm/fmod.c b/jerry-libm/fmod.c
index bb58bb163..7a74bf3f6 100644
--- a/jerry-libm/fmod.c
+++ b/jerry-libm/fmod.c
@@ -35,8 +35,6 @@
 
 static const double Zero[] = { 0.0, -0.0, };
 
-#define one 1.0
-
 double
 fmod (double x, double y)
 {
@@ -201,11 +199,13 @@ fmod (double x, double y)
     lx = lx + lx;
     iy -= 1;
   }
+
+  double_accessor ret;
   if (iy >= -1022) /* normalize output */
   {
     hx = ((hx - 0x00100000) | ((iy + 1023) << 20));
-    __HI (x) = hx | sx;
-    __LO (x) = lx;
+    ret.as_int.hi = hx | sx;
+    ret.as_int.lo = lx;
   }
   else /* subnormal output */
   {
@@ -225,11 +225,8 @@ fmod (double x, double y)
       lx = hx >> (n - 32);
       hx = sx;
     }
-    __HI (x) = hx | sx;
-    __LO (x) = lx;
-    x *= one; /* create necessary signal */
+    ret.as_int.hi = hx | sx;
+    ret.as_int.lo = lx;
   }
-  return x; /* exact output */
+  return ret.dbl; /* exact output */
 } /* fmod */
-
-#undef one
diff --git a/jerry-libm/jerry-libm-internal.h b/jerry-libm/jerry-libm-internal.h
index 4c6e68c6f..fb29c7f44 100644
--- a/jerry-libm/jerry-libm-internal.h
+++ b/jerry-libm/jerry-libm-internal.h
@@ -48,13 +48,36 @@
 #endif /* !__LITTLE_ENDIAN */
 
 #ifdef __LITTLE_ENDIAN
-#define __HI(x) *(1 + (int *) &x)
-#define __LO(x) *(int *) &x
+#define __HI(x) *(1 + (const int *) &x)
+#define __LO(x) *(const int *) &x
+typedef union
+{
+  double dbl;
+  struct
+  {
+    int lo;
+    int hi;
+  } as_int;
+} double_accessor;
 #else /* !__LITTLE_ENDIAN */
-#define __HI(x) *(int *) &x
-#define __LO(x) *(1 + (int *) &x)
+#define __HI(x) *(const int *) &x
+#define __LO(x) *(1 + (const int *) &x)
+
+typedef union
+{
+  double dbl;
+  struct
+  {
+    int hi;
+    int lo;
+  } as_int;
+} double_accessor;
 #endif /* __LITTLE_ENDIAN */
 
+#ifndef NAN
+#define NAN (0.0/0.0)
+#endif
+
 /*
  * ANSI/POSIX
  */
diff --git a/jerry-libm/log.c b/jerry-libm/log.c
index 7c9e56944..ed7152ac7 100644
--- a/jerry-libm/log.c
+++ b/jerry-libm/log.c
@@ -122,9 +122,13 @@ log (double x)
   k += (hx >> 20) - 1023;
   hx &= 0x000fffff;
   i = (hx + 0x95f64) & 0x100000;
-  __HI (x) = hx | (i ^ 0x3ff00000); /* normalize x or x / 2 */
+
+  double_accessor temp;
+  temp.dbl = x;
+  temp.as_int.hi = hx | (i ^ 0x3ff00000); /* normalize x or x / 2 */
   k += (i >> 20);
-  f = x - 1.0;
+  f = temp.dbl - 1.0;
+
   if ((0x000fffff & (2 + hx)) < 3) /* |f| < 2**-20 */
   {
     if (f == zero)
diff --git a/jerry-libm/nextafter.c b/jerry-libm/nextafter.c
index df6f4476c..f9473d5a7 100644
--- a/jerry-libm/nextafter.c
+++ b/jerry-libm/nextafter.c
@@ -33,6 +33,7 @@ nextafter (double x,
 {
   int hx, hy, ix, iy;
   unsigned lx, ly;
+  double_accessor ret;
 
   hx = __HI (x); /* high word of x */
   lx = __LO (x); /* low  word of x */
@@ -54,16 +55,16 @@ nextafter (double x,
 
   if ((ix | lx) == 0)
   { /* x == 0 */
-    __HI (x) = hy & 0x80000000; /* return +-minsubnormal */
-    __LO (x) = 1;
-    y = x * x;
-    if (y == x)
+    ret.as_int.hi = hy & 0x80000000; /* return +-minsubnormal */
+    ret.as_int.lo = 1;
+    y = ret.dbl * ret.dbl;
+    if (y == ret.dbl)
     {
       return y;
     }
     else
     {
-      return x; /* raise underflow flag */
+      return ret.dbl; /* raise underflow flag */
     }
   }
 
@@ -122,13 +123,13 @@ nextafter (double x,
     y = x * x;
     if (y != x)
     { /* raise underflow flag */
-      __HI (y) = hx;
-      __LO (y) = lx;
-      return y;
+      ret.as_int.hi = hx;
+      ret.as_int.lo = lx;
+      return ret.dbl;
     }
   }
 
-  __HI (x) = hx;
-  __LO (x) = lx;
-  return x;
+  ret.as_int.hi = hx;
+  ret.as_int.lo = lx;
+  return ret.dbl;
 } /* nextafter */
diff --git a/jerry-libm/pow.c b/jerry-libm/pow.c
index 18f2bc17a..581876c1d 100644
--- a/jerry-libm/pow.c
+++ b/jerry-libm/pow.c
@@ -120,8 +120,9 @@ static const double dp_l[] =
 double
 pow (double x, double y)
 {
-  double z, ax, z_h, z_l, p_h, p_l;
-  double y1, t1, t2, r, s, t, u, v, w;
+  double_accessor t1, ax, p_h, y1, t, z;
+  double z_h, z_l, p_l;
+  double t2, r, s, u, v, w;
   int i, j, k, yisint, n;
   int hx, hy, ix, iy;
   unsigned lx, ly;
@@ -227,29 +228,29 @@ pow (double x, double y)
     }
   }
 
-  ax = fabs (x);
+  ax.dbl = fabs (x);
   /* special value of x */
   if (lx == 0)
   {
     if (ix == 0x7ff00000 || ix == 0 || ix == 0x3ff00000)
     {
-      z = ax; /* x is +-0,+-inf,+-1 */
+      z.dbl = ax.dbl; /* x is +-0,+-inf,+-1 */
       if (hy < 0)
       {
-        z = one / z; /* z = (1 / |x|) */
+        z.dbl = one / z.dbl; /* z = (1 / |x|) */
       }
       if (hx < 0)
       {
         if (((ix - 0x3ff00000) | yisint) == 0)
         {
-          z = (z - z) / (z - z); /* (-1)**non-int is NaN */
+          z.dbl = NAN; /* (-1)**non-int is NaN */
         }
         else if (yisint == 1)
         {
-          z = -z; /* (x<0)**odd = -(|x|**odd) */
+          z.dbl = -z.dbl; /* (x<0)**odd = -(|x|**odd) */
         }
       }
-      return z;
+      return z.dbl;
     }
   }
 
@@ -292,25 +293,26 @@ pow (double x, double y)
     }
     /* now |1 - x| is tiny <= 2**-20, suffice to compute
        log(x) by x - x^2 / 2 + x^3 / 3 - x^4 / 4 */
-    t = ax - one; /* t has 20 trailing zeros */
-    w = (t * t) * (0.5 - t * (0.3333333333333333333333 - t * 0.25));
-    u = ivln2_h * t; /* ivln2_h has 21 sig. bits */
-    v = t * ivln2_l - w * ivln2;
-    t1 = u + v;
-    __LO (t1) = 0;
-    t2 = v - (t1 - u);
+    t.dbl = ax.dbl - one; /* t has 20 trailing zeros */
+    w = (t.dbl * t.dbl) * (0.5 - t.dbl * (0.3333333333333333333333 - t.dbl * 0.25));
+    u = ivln2_h * t.dbl; /* ivln2_h has 21 sig. bits */
+    v = t.dbl * ivln2_l - w * ivln2;
+    t1.dbl = u + v;
+    t1.as_int.lo = 0;
+    t2 = v - (t1.dbl - u);
   }
   else
   {
-    double ss, s2, s_h, s_l, t_h, t_l;
+    double_accessor s_h, t_h;
+    double ss, s2, s_l, t_l;
 
     n = 0;
     /* take care subnormal number */
     if (ix < 0x00100000)
     {
-      ax *= two53;
+      ax.dbl *= two53;
       n -= 53;
-      ix = __HI (ax);
+      ix = ax.as_int.hi;
     }
     n += ((ix) >> 20) - 0x3ff;
     j = ix & 0x000fffff;
@@ -330,51 +332,51 @@ pow (double x, double y)
       n += 1;
       ix -= 0x00100000;
     }
-    __HI (ax) = ix;
+    ax.as_int.hi = ix;
 
     /* compute ss = s_h + s_l = (x - 1) / (x + 1) or (x - 1.5) / (x + 1.5) */
-    u = ax - bp[k]; /* bp[0] = 1.0, bp[1] = 1.5 */
-    v = one / (ax + bp[k]);
+    u = ax.dbl - bp[k]; /* bp[0] = 1.0, bp[1] = 1.5 */
+    v = one / (ax.dbl + bp[k]);
     ss = u * v;
-    s_h = ss;
-    __LO (s_h) = 0;
+    s_h.dbl = ss;
+    s_h.as_int.lo = 0;
     /* t_h = ax + bp[k] High */
-    t_h = zero;
-    __HI (t_h) = ((ix >> 1) | 0x20000000) + 0x00080000 + (k << 18);
-    t_l = ax - (t_h - bp[k]);
-    s_l = v * ((u - s_h * t_h) - s_h * t_l);
+    t_h.dbl = zero;
+    t_h.as_int.hi = ((ix >> 1) | 0x20000000) + 0x00080000 + (k << 18);
+    t_l = ax.dbl - (t_h.dbl - bp[k]);
+    s_l = v * ((u - s_h.dbl * t_h.dbl) - s_h.dbl * t_l);
     /* compute log(ax) */
     s2 = ss * ss;
     r = s2 * s2 * (L1 + s2 * (L2 + s2 * (L3 + s2 * (L4 + s2 * (L5 + s2 * L6)))));
-    r += s_l * (s_h + ss);
-    s2 = s_h * s_h;
-    t_h = 3.0 + s2 + r;
-    __LO (t_h) = 0;
-    t_l = r - ((t_h - 3.0) - s2);
+    r += s_l * (s_h.dbl + ss);
+    s2 = s_h.dbl * s_h.dbl;
+    t_h.dbl = 3.0 + s2 + r;
+    t_h.as_int.lo = 0;
+    t_l = r - ((t_h.dbl - 3.0) - s2);
     /* u + v = ss * (1 + ...) */
-    u = s_h * t_h;
-    v = s_l * t_h + t_l * ss;
+    u = s_h.dbl * t_h.dbl;
+    v = s_l * t_h.dbl + t_l * ss;
     /* 2 / (3 * log2) * (ss + ...) */
-    p_h = u + v;
-    __LO (p_h) = 0;
-    p_l = v - (p_h - u);
-    z_h = cp_h * p_h; /* cp_h + cp_l = 2 / (3 * log2) */
-    z_l = cp_l * p_h + p_l * cp + dp_l[k];
+    p_h.dbl = u + v;
+    p_h.as_int.lo = 0;
+    p_l = v - (p_h.dbl - u);
+    z_h = cp_h * p_h.dbl; /* cp_h + cp_l = 2 / (3 * log2) */
+    z_l = cp_l * p_h.dbl + p_l * cp + dp_l[k];
     /* log2(ax) = (ss + ...) * 2 / (3 * log2) = n + dp_h + z_h + z_l */
-    t = (double) n;
-    t1 = (((z_h + z_l) + dp_h[k]) + t);
-    __LO (t1) = 0;
-    t2 = z_l - (((t1 - t) - dp_h[k]) - z_h);
+    t.dbl = (double) n;
+    t1.dbl = (((z_h + z_l) + dp_h[k]) + t.dbl);
+    t1.as_int.lo = 0;
+    t2 = z_l - (((t1.dbl - t.dbl) - dp_h[k]) - z_h);
   }
 
   /* split up y into y1 + y2 and compute (y1 + y2) * (t1 + t2) */
-  y1 = y;
-  __LO (y1) = 0;
-  p_l = (y - y1) * t1 + y * t2;
-  p_h = y1 * t1;
-  z = p_l + p_h;
-  j = __HI (z);
-  i = __LO (z);
+  y1.dbl = y;
+  y1.as_int.lo = 0;
+  p_l = (y - y1.dbl) * t1.dbl + y * t2;
+  p_h.dbl = y1.dbl * t1.dbl;
+  z.dbl = p_l + p_h.dbl;
+  j = z.as_int.hi;
+  i = z.as_int.lo;
   if (j >= 0x40900000) /* z >= 1024 */
   {
     if (((j - 0x40900000) | i) != 0) /* if z > 1024 */
@@ -383,7 +385,7 @@ pow (double x, double y)
     }
     else
     {
-      if (p_l + ovt > z - p_h)
+      if (p_l + ovt > z.dbl - p_h.dbl)
       {
         return s * huge * huge; /* overflow */
       }
@@ -397,7 +399,7 @@ pow (double x, double y)
     }
     else
     {
-      if (p_l <= z - p_h)
+      if (p_l <= z.dbl - p_h.dbl)
       {
         return s * tiny * tiny; /* underflow */
       }
@@ -413,36 +415,36 @@ pow (double x, double y)
   {
     n = j + (0x00100000 >> (k + 1));
     k = ((n & 0x7fffffff) >> 20) - 0x3ff; /* new k for n */
-    t = zero;
-    __HI (t) = (n & ~(0x000fffff >> k));
+    t.dbl = zero;
+    t.as_int.hi = (n & ~(0x000fffff >> k));
     n = ((n & 0x000fffff) | 0x00100000) >> (20 - k);
     if (j < 0)
     {
       n = -n;
     }
-    p_h -= t;
+    p_h.dbl -= t.dbl;
   }
-  t = p_l + p_h;
-  __LO (t) = 0;
-  u = t * lg2_h;
-  v = (p_l - (t - p_h)) * lg2 + t * lg2_l;
-  z = u + v;
-  w = v - (z - u);
-  t = z * z;
-  t1 = z - t * (P1 + t * (P2 + t * (P3 + t * (P4 + t * P5))));
-  r = (z * t1) / (t1 - two) - (w + z * w);
-  z = one - (r - z);
-  j = __HI (z);
+  t.dbl = p_l + p_h.dbl;
+  t.as_int.lo = 0;
+  u = t.dbl * lg2_h;
+  v = (p_l - (t.dbl - p_h.dbl)) * lg2 + t.dbl * lg2_l;
+  z.dbl = u + v;
+  w = v - (z.dbl - u);
+  t.dbl = z.dbl * z.dbl;
+  t1.dbl = z.dbl - t.dbl * (P1 + t.dbl * (P2 + t.dbl * (P3 + t.dbl * (P4 + t.dbl * P5))));
+  r = (z.dbl * t1.dbl) / (t1.dbl - two) - (w + z.dbl * w);
+  z.dbl = one - (r - z.dbl);
+  j = z.as_int.hi;
   j += (n << 20);
   if ((j >> 20) <= 0) /* subnormal output */
   {
-    z = scalbn (z, n);
+    z.dbl = scalbn (z.dbl, n);
   }
   else
   {
-    __HI (z) += (n << 20);
+    z.as_int.hi += (n << 20);
   }
-  return s * z;
+  return s * z.dbl;
 } /* pow */
 
 #undef zero
diff --git a/jerry-libm/scalbn.c b/jerry-libm/scalbn.c
index 2ee4f355d..4c61b5af0 100644
--- a/jerry-libm/scalbn.c
+++ b/jerry-libm/scalbn.c
@@ -70,8 +70,10 @@ scalbn (double x, int n)
   }
   if (k > 0) /* normal result */
   {
-    __HI (x) = (hx & 0x800fffff) | (k << 20);
-    return x;
+    double_accessor ret;
+    ret.dbl = x;
+    ret.as_int.hi = (hx & 0x800fffff) | (k << 20);
+    return ret.dbl;
   }
   if (k <= -54)
   {
@@ -85,8 +87,10 @@ scalbn (double x, int n)
     }
   }
   k += 54; /* subnormal result */
-  __HI (x) = (hx & 0x800fffff) | (k << 20);
-  return x * twom54;
+  double_accessor ret;
+  ret.dbl = x;
+  ret.as_int.hi = (hx & 0x800fffff) | (k << 20);
+  return ret.dbl * twom54;
 } /* scalbn */
 
 #undef two54
diff --git a/jerry-libm/sqrt.c b/jerry-libm/sqrt.c
index 43135351b..fd45a6f59 100644
--- a/jerry-libm/sqrt.c
+++ b/jerry-libm/sqrt.c
@@ -104,7 +104,6 @@
 double
 sqrt (double x)
 {
-  double z;
   int sign = (int) 0x80000000;
   unsigned r, t1, s1, ix1, q1;
   int ix0, s0, q, m, t, i;
@@ -201,19 +200,21 @@ sqrt (double x)
     r >>= 1;
   }
 
+  double_accessor ret;
+
   /* use floating add to find out rounding direction */
   if ((ix0 | ix1) != 0)
   {
-    z = one - tiny; /* trigger inexact flag */
-    if (z >= one)
+    ret.dbl = one - tiny; /* trigger inexact flag */
+    if (ret.dbl >= one)
     {
-      z = one + tiny;
+      ret.dbl = one + tiny;
       if (q1 == (unsigned) 0xffffffff)
       {
         q1 = 0;
         q += 1;
       }
-      else if (z > one)
+      else if (ret.dbl > one)
       {
         if (q1 == (unsigned) 0xfffffffe)
         {
@@ -234,9 +235,9 @@ sqrt (double x)
     ix1 |= sign;
   }
   ix0 += (m << 20);
-  __HI (z) = ix0;
-  __LO (z) = ix1;
-  return z;
+  ret.as_int.hi = ix0;
+  ret.as_int.lo = ix1;
+  return ret.dbl;
 } /* sqrt */
 
 #undef one
diff --git a/jerry-libm/trig.c b/jerry-libm/trig.c
index dd2440d22..4211571e0 100644
--- a/jerry-libm/trig.c
+++ b/jerry-libm/trig.c
@@ -475,7 +475,8 @@ static const int npio2_hw[] =
 static int
 __ieee754_rem_pio2 (double x, double *y)
 {
-  double z, w, t, r, fn;
+  double_accessor z;
+  double w, t, r, fn;
   double tx[3];
   int e0, i, j, nx, n, ix, hx;
 
@@ -491,33 +492,33 @@ __ieee754_rem_pio2 (double x, double *y)
   {
     if (hx > 0)
     {
-      z = x - pio2_1;
+      z.dbl = x - pio2_1;
       if (ix != 0x3ff921fb) /* 33 + 53 bit pi is good enough */
       {
-        y[0] = z - pio2_1t;
-        y[1] = (z - y[0]) - pio2_1t;
+        y[0] = z.dbl - pio2_1t;
+        y[1] = (z.dbl - y[0]) - pio2_1t;
       }
       else /* near pi/2, use 33 + 33 + 53 bit pi */
       {
-        z -= pio2_2;
-        y[0] = z - pio2_2t;
-        y[1] = (z - y[0]) - pio2_2t;
+        z.dbl -= pio2_2;
+        y[0] = z.dbl - pio2_2t;
+        y[1] = (z.dbl - y[0]) - pio2_2t;
       }
       return 1;
     }
     else /* negative x */
     {
-      z = x + pio2_1;
+      z.dbl = x + pio2_1;
       if (ix != 0x3ff921fb) /* 33 + 53 bit pi is good enough */
       {
-        y[0] = z + pio2_1t;
-        y[1] = (z - y[0]) + pio2_1t;
+        y[0] = z.dbl + pio2_1t;
+        y[1] = (z.dbl - y[0]) + pio2_1t;
       }
       else /* near pi/2, use 33 + 33 + 53 bit pi */
       {
-        z += pio2_2;
-        y[0] = z + pio2_2t;
-        y[1] = (z - y[0]) + pio2_2t;
+        z.dbl += pio2_2;
+        y[0] = z.dbl + pio2_2t;
+        y[1] = (z.dbl - y[0]) + pio2_2t;
       }
       return -1;
     }
@@ -577,15 +578,15 @@ __ieee754_rem_pio2 (double x, double *y)
     return 0;
   }
   /* set z = scalbn(|x|, ilogb(x) - 23) */
-  __LO (z) = __LO (x);
+  z.as_int.lo = __LO (x);
   e0 = (ix >> 20) - 1046; /* e0 = ilogb(z) - 23; */
-  __HI (z) = ix - (e0 << 20);
+  z.as_int.hi = ix - (e0 << 20);
   for (i = 0; i < 2; i++)
   {
-    tx[i] = (double) ((int) (z));
-    z = (z - tx[i]) * two24;
+    tx[i] = (double) ((int) (z.dbl));
+    z.dbl = (z.dbl - tx[i]) * two24;
   }
-  tx[2] = z;
+  tx[2] = z.dbl;
   nx = 3;
   while (tx[nx - 1] == zero) /* skip zero term */
   {
@@ -708,7 +709,7 @@ __kernel_sin (double x, double y, int iy)
 static double
 __kernel_cos (double x, double y)
 {
-  double a, hz, z, r, qx;
+  double a, hz, z, r;
   int ix;
 
   ix = __HI (x) & 0x7fffffff; /* ix = |x|'s high word */
@@ -727,17 +728,18 @@ __kernel_cos (double x, double y)
   }
   else
   {
+    double_accessor qx;
     if (ix > 0x3fe90000) /* x > 0.78125 */
     {
-      qx = 0.28125;
+      qx.dbl = 0.28125;
     }
     else
     {
-      __HI (qx) = ix - 0x00200000; /* x / 4 */
-      __LO (qx) = 0;
+      qx.as_int.hi = ix - 0x00200000; /* x / 4 */
+      qx.as_int.lo = 0;
     }
-    hz = 0.5 * z - qx;
-    a = one - qx;
+    hz = 0.5 * z - qx.dbl;
+    a = one - qx.dbl;
     return a - (hz - (z * r - x * y));
   }
 } /* __kernel_cos */
@@ -794,7 +796,8 @@ __kernel_cos (double x, double y)
 static double
 __kernel_tan (double x, double y, int iy)
 {
-  double z, r, v, w, s;
+  double_accessor z;
+  double r, v, w, s;
   int ix, hx;
 
   hx = __HI (x); /* high word of x */
@@ -815,15 +818,16 @@ __kernel_tan (double x, double y, int iy)
         }
         else /* compute -1 / (x + y) carefully */
         {
-          double a, t;
+          double a;
+          double_accessor t;
 
-          z = w = x + y;
-          __LO (z) = 0;
-          v = y - (z - x);
-          t = a = -one / w;
-          __LO (t) = 0;
-          s = one + t * z;
-          return t + a * (s + t * v);
+          z.dbl = w = x + y;
+          z.as_int.lo = 0;
+          v = y - (z.dbl - x);
+          t.dbl = a = -one / w;
+          t.as_int.lo = 0;
+          s = one + t.dbl * z.dbl;
+          return t.dbl + a * (s + t.dbl * v);
         }
       }
     }
@@ -835,22 +839,22 @@ __kernel_tan (double x, double y, int iy)
       x = -x;
       y = -y;
     }
-    z = pio4 - x;
+    z.dbl = pio4 - x;
     w = pio4lo - y;
-    x = z + w;
+    x = z.dbl + w;
     y = 0.0;
   }
-  z = x * x;
-  w = z * z;
+  z.dbl = x * x;
+  w = z.dbl * z.dbl;
   /*
    * Break x^5 * (T[1] + x^2 * T[2] + ...) into
    * x^5 (T[1] + x^4 * T[3] + ... + x^20 * T[11]) +
    * x^5 (x^2 * (T[2] + x^4 * T[4] + ... + x^22 * [T12]))
    */
   r = T1 + w * (T3 + w * (T5 + w * (T7 + w * (T9 + w * T11))));
-  v = z * (T2 + w * (T4 + w * (T6 + w * (T8 + w * (T10 + w * T12)))));
-  s = z * x;
-  r = y + z * (s * (r + v) + y);
+  v = z.dbl * (T2 + w * (T4 + w * (T6 + w * (T8 + w * (T10 + w * T12)))));
+  s = z.dbl * x;
+  r = y + z.dbl * (s * (r + v) + y);
   r += T0 * s;
   w = x + r;
   if (ix >= 0x3FE59428)
@@ -869,15 +873,16 @@ __kernel_tan (double x, double y, int iy)
      * -1.0 / (x + r) here
      */
     /* compute -1.0 / (x + r) accurately */
-    double a, t;
+    double a;
+    double_accessor t;
 
-    z = w;
-    __LO (z) = 0;
-    v = r - (z - x); /* z + v = r + x */
-    t = a = -1.0 / w; /* a = -1.0 / w */
-    __LO (t) = 0;
-    s = 1.0 + t * z;
-    return t + a * (s + t * v);
+    z.dbl = w;
+    z.as_int.lo = 0;
+    v = r - (z.dbl - x); /* z + v = r + x */
+    t.dbl = a = -1.0 / w; /* a = -1.0 / w */
+    t.as_int.lo = 0;
+    s = 1.0 + t.dbl * z.dbl;
+    return t.dbl + a * (s + t.dbl * v);
   }
 } /* __kernel_tan */