diff --git a/src/pc/gfx/gfx_direct3d_common.cpp b/src/pc/gfx/gfx_direct3d_common.cpp
index 5b5eff36d..289271b78 100644
--- a/src/pc/gfx/gfx_direct3d_common.cpp
+++ b/src/pc/gfx/gfx_direct3d_common.cpp
@@ -274,6 +274,7 @@ void gfx_direct3d_common_build_shader(char buf[4096], size_t& len, size_t& num_f
             } else {
                 append_line(buf, &len, "    float4 texVal1 = g_texture1.Sample(g_sampler1, input.lightmap);");
             }
+            append_line(buf, &len, "    texVal1.rgb = texVal1.rgb * texVal1.rgb + texVal1.rgb;");
         } else {
             if (three_point_filtering) {
                 append_line(buf, &len, "    float4 texVal1;");
diff --git a/src/pc/gfx/gfx_opengl.c b/src/pc/gfx/gfx_opengl.c
index fb168d368..d3e2d20f4 100644
--- a/src/pc/gfx/gfx_opengl.c
+++ b/src/pc/gfx/gfx_opengl.c
@@ -383,22 +383,26 @@ static struct ShaderProgram *gfx_opengl_create_and_load_new_shader(struct ColorC
         }
     }
 
-    append_str(fs_buf, &fs_len, (opt_alpha) ? "vec4 texel = " : "vec3 texel = ");
-    for (int i = 0; i < (opt_2cycle + 1); i++) {
-        u8* cmd = &cc->shader_commands[i * 8];
-        if (!ccf.color_alpha_same[i] && opt_alpha) {
-            append_str(fs_buf, &fs_len, "vec4(");
-            append_formula(fs_buf, &fs_len, cmd, ccf.do_single[i*2+0], ccf.do_multiply[i*2+0], ccf.do_mix[i*2+0], false, false, true);
-            append_str(fs_buf, &fs_len, ", ");
-            append_formula(fs_buf, &fs_len, cmd, ccf.do_single[i*2+1], ccf.do_multiply[i*2+1], ccf.do_mix[i*2+1], true, true, true);
-            append_str(fs_buf, &fs_len, ")");
-        } else {
-            append_formula(fs_buf, &fs_len, cmd, ccf.do_single[i*2+0], ccf.do_multiply[i*2+0], ccf.do_mix[i*2+0], opt_alpha, false, opt_alpha);
-        }
-        append_line(fs_buf, &fs_len, ";");
+    if (opt_light_map) {
+        append_str(fs_buf, &fs_len, "vec3 texel = texVal0.rgb * (texVal1.rgb * texVal1.rgb + texVal1.rgb);\n");
+    } else {
+        append_str(fs_buf, &fs_len, (opt_alpha) ? "vec4 texel = " : "vec3 texel = ");
+        for (int i = 0; i < (opt_2cycle + 1); i++) {
+            u8* cmd = &cc->shader_commands[i * 8];
+            if (!ccf.color_alpha_same[i] && opt_alpha) {
+                append_str(fs_buf, &fs_len, "vec4(");
+                append_formula(fs_buf, &fs_len, cmd, ccf.do_single[i*2+0], ccf.do_multiply[i*2+0], ccf.do_mix[i*2+0], false, false, true);
+                append_str(fs_buf, &fs_len, ", ");
+                append_formula(fs_buf, &fs_len, cmd, ccf.do_single[i*2+1], ccf.do_multiply[i*2+1], ccf.do_mix[i*2+1], true, true, true);
+                append_str(fs_buf, &fs_len, ")");
+            } else {
+                append_formula(fs_buf, &fs_len, cmd, ccf.do_single[i*2+0], ccf.do_multiply[i*2+0], ccf.do_mix[i*2+0], opt_alpha, false, opt_alpha);
+            }
+            append_line(fs_buf, &fs_len, ";");
 
-        if (i == 0 && opt_2cycle) {
-            append_str(fs_buf, &fs_len, "texel = ");
+            if (i == 0 && opt_2cycle) {
+                append_str(fs_buf, &fs_len, "texel = ");
+            }
         }
     }