--- gap/gap_colordiff.c.orig	2018-03-22 12:44:19.000000000 -0700
+++ gap/gap_colordiff.c	2018-03-22 12:46:38.000000000 -0700
@@ -635,7 +635,7 @@
   gdouble delta_L_prime = lab2.L - lab1.L;
   gdouble delta_C_prime = C_prime_2 - C_prime_1;
 
-  gdouble h_bar = abs(h_prime_1 - h_prime_2);
+  gdouble h_bar = fabs(h_prime_1 - h_prime_2);
   gdouble delta_h_prime;
   if (C_prime_1 * C_prime_2 == 0) delta_h_prime = 0;
   else
@@ -681,8 +681,8 @@
   gdouble L_prime_average_minus_50_square = (L_prime_average - 50);
   L_prime_average_minus_50_square *= L_prime_average_minus_50_square;
 
-  gdouble S_L = 1 + ((.015d * L_prime_average_minus_50_square) / sqrt(20 + L_prime_average_minus_50_square));
-  gdouble S_C = 1 + .045d * C_prime_average;
+  gdouble S_L = 1 + ((.015 * L_prime_average_minus_50_square) / sqrt(20 + L_prime_average_minus_50_square));
+  gdouble S_C = 1 + .045 * C_prime_average;
   gdouble T = 1
       - .17 * cos(gimp_deg_to_rad(h_prime_average - 30))
       + .24 * cos(gimp_deg_to_rad(h_prime_average * 2))