diff --git a/app/operations/gimpoperationlevels.c b/app/operations/gimpoperationlevels.c
index 63d6d21cd4..e06534473d 100644
--- a/app/operations/gimpoperationlevels.c
+++ b/app/operations/gimpoperationlevels.c
@@ -202,7 +202,7 @@ gimp_operation_levels_map_input (GimpLevelsConfig     *config,
   else
     value = (value - config->low_input[channel]);
 
-  if (config->gamma[channel] != 0.0)
+  if (config->gamma[channel] != 0.0 && value > 0.0)
     value = pow (value, 1.0 / config->gamma[channel]);
 
   return value;