*** 121,131 ****
  #define Lp7     xxx[9]
  #define zero    xxx[10]
  
  double
  log1p(double x) {
!         double  hfsq, f, c, s, z, R, u;
          int     k, hx, hu, ax;
  
          hx = ((int *)&x)[HIWORD];               /* high word of x */
          ax = hx & 0x7fffffff;
  
--- 121,131 ----
  #define Lp7     xxx[9]
  #define zero    xxx[10]
  
  double
  log1p(double x) {
!         double  hfsq, f, c = 0.0, s, z, R, u;
          int     k, hx, hu, ax;
  
          hx = ((int *)&x)[HIWORD];               /* high word of x */
          ax = hx & 0x7fffffff;
  
*** 150,159 ****
--- 150,160 ----
                          k = 0;
                          f = x;
                          hu = 1;
                  }
          }
+         /* We will initialize 'c' here. */
          if (k != 0) {
                  if (hx < 0x43400000) {
                          u = 1.0 + x;
                          hu = ((int *)&u)[HIWORD];       /* high word of u */
                          k = (hu >> 20) - 1023;
*** 181,190 ****
--- 182,192 ----
          hfsq = 0.5 * f * f;
          if (hu == 0) {          /* |f| < 2**-20 */
                  if (f == zero) {
                          if (k == 0)
                                  return (zero);
+                         /* We already initialized 'c' before, when (k != 0) */
                          c += k * ln2_lo;
                          return (k * ln2_hi + c);
                  }
                  R = hfsq * (1.0 - 0.66666666666666666 * f);
                  if (k == 0)