diff --git a/config.cpp b/config.cpp
index b8ab1118..e47df9b6 100644
--- a/config.cpp
+++ b/config.cpp
@@ -492,6 +492,8 @@ EX const char *conffile = "hyperrogue.ini";
 /* extra space if more geometries are added */
 EX array<ld, gGUARD+64> sightranges;
 
+EX bool logfog;
+
 EX videopar vid;
 
 #define DEFAULT_WALLMODE (ISMOBILE ? 3 : 5)
@@ -774,6 +776,8 @@ EX void initConfig() {
 
   param_b(vid.darkhepta, "mark heptagons", false);
   
+  param_b(logfog, "logfog", false);
+
   for(auto& lp: linepatterns::patterns) {
     addsaver(lp->color, "lpcolor-" + lp->lpname);
     addsaver(lp->multiplier, "lpwidth-" + lp->lpname);
diff --git a/shaders.cpp b/shaders.cpp
index 31a4d286..5a384773 100644
--- a/shaders.cpp
+++ b/shaders.cpp
@@ -402,7 +402,10 @@ shared_ptr<glhr::GLprogram> write_shader(flagtype shader_flags) {
       }
     else if(distfun != "") {
       have_vfogs = true;
-      vmain += "vFogs = (uFogBase - " + distfun + " / uFog);\n";
+      if(logfog)
+        vmain += "vFogs = uFogBase * exp(- " + distfun + " / uFog);\n";
+      else
+        vmain += "vFogs = clamp(uFogBase - " + distfun + " / uFog, 0.0, 1.0);\n";
       vsh += 
         "uniform mediump float uFog;\n"
         "uniform mediump float uFogBase;\n";