diff --git a/rtdata/iccprofiles/output/RTv2_Medium.icc b/rtdata/iccprofiles/output/RTv2_Medium.icc
index 065c43bc4..454f40d90 100644
Binary files a/rtdata/iccprofiles/output/RTv2_Medium.icc and b/rtdata/iccprofiles/output/RTv2_Medium.icc differ
diff --git a/rtengine/iplab2rgb.cc b/rtengine/iplab2rgb.cc
index b2fd20cb8..9094f3526 100644
--- a/rtengine/iplab2rgb.cc
+++ b/rtengine/iplab2rgb.cc
@@ -367,8 +367,12 @@ Imagefloat* ImProcFunctions::lab2rgbOut(LabImage* lab, int cx, int cy, int cw, i
         gammaParams[6] = 0.0;
 
         cmsToneCurve* GammaTRC[3];
-
-        GammaTRC[0] = GammaTRC[1] = GammaTRC[2] = cmsBuildParametricToneCurve(nullptr, 5, gammaParams); //5 = smoother than 4
+        if(slopetag == 0.) {
+            GammaTRC[0] = GammaTRC[1] = GammaTRC[2] = cmsBuildGamma(NULL, gammatag);
+        }
+        else {
+            GammaTRC[0] = GammaTRC[1] = GammaTRC[2] = cmsBuildParametricToneCurve(nullptr, 5, gammaParams); //5 = smoother than 4
+        }
         cmsWriteTag(oprof, cmsSigRedTRCTag, GammaTRC[0]);
         cmsWriteTag(oprof, cmsSigGreenTRCTag, GammaTRC[1]);
         cmsWriteTag(oprof, cmsSigBlueTRCTag, GammaTRC[2]);
diff --git a/rtgui/iccprofilecreator.cc b/rtgui/iccprofilecreator.cc
index 03d46471d..97d22ca0b 100644
--- a/rtgui/iccprofilecreator.cc
+++ b/rtgui/iccprofilecreator.cc
@@ -1310,6 +1310,8 @@ void ICCProfileCreator::savePressed()
         GammaTRC[0] = GammaTRC[1] = GammaTRC[2] = cmsBuildGamma(NULL, 1.80078125);
     } else if (gammaPreset == "linear_g1.0") {
         GammaTRC[0] = GammaTRC[1] = GammaTRC[2] = cmsBuildGamma(NULL, 1.0);
+    } else if(gammaPreset == "Custom" && slope == 0.0) {
+        GammaTRC[0] = GammaTRC[1] = GammaTRC[2] = cmsBuildGamma(NULL, gamma);
     } else {
         GammaTRC[0] = GammaTRC[1] = GammaTRC[2] = cmsBuildParametricToneCurve(nullptr, 5, ga);
     }