diff --git a/binaries/data/mods/mod/shaders/glsl/terrain_common.fs b/binaries/data/mods/mod/shaders/glsl/terrain_common.fs
index 6a1e3e049f..d5d40975ae 100644
--- a/binaries/data/mods/mod/shaders/glsl/terrain_common.fs
+++ b/binaries/data/mods/mod/shaders/glsl/terrain_common.fs
@@ -89,8 +89,7 @@ void main()
   #endif
 
   #if USE_NORMAL_MAP
-    float sign = v_tangent.w;
-    mat3 tbn = mat3(v_tangent.xyz, v_bitangent * -sign, v_normal);
+    mat3 tbn = mat3(v_tangent, v_bitangent, v_normal);
     #if USE_TRIPLANAR
       vec3 ntex = triplanarNormals(GET_DRAW_TEXTURE_2D(normTex), v_tex).rgb;
     #else
diff --git a/binaries/data/mods/mod/shaders/glsl/terrain_common.h b/binaries/data/mods/mod/shaders/glsl/terrain_common.h
index 8000c6268f..3d12186ddb 100644
--- a/binaries/data/mods/mod/shaders/glsl/terrain_common.h
+++ b/binaries/data/mods/mod/shaders/glsl/terrain_common.h
@@ -49,7 +49,7 @@ VERTEX_OUTPUT(3, vec3, v_tex);
 VERTEX_OUTPUT(3, vec2, v_tex);
 #endif
 #if USE_NORMAL_MAP
-VERTEX_OUTPUT(4, vec4, v_tangent);
+VERTEX_OUTPUT(4, vec3, v_tangent);
 VERTEX_OUTPUT(5, vec3, v_bitangent);
 #endif
 #if USE_SPECULAR_MAP
diff --git a/binaries/data/mods/mod/shaders/glsl/terrain_common.vs b/binaries/data/mods/mod/shaders/glsl/terrain_common.vs
index 579f323c0e..3de77021b3 100644
--- a/binaries/data/mods/mod/shaders/glsl/terrain_common.vs
+++ b/binaries/data/mods/mod/shaders/glsl/terrain_common.vs
@@ -57,10 +57,13 @@ void main()
 
   #if USE_NORMAL_MAP || USE_SPECULAR_MAP || USE_TRIPLANAR
     #if USE_NORMAL_MAP
-      vec3 t = vec3(1.0, 0.0, 0.0);
-      t = normalize(t - v_normal * dot(v_normal, t));
-      v_tangent = vec4(t, -1.0);
-      v_bitangent = cross(v_normal, t);
+      #if DECAL || USE_TRIPLANAR
+        // TODO: this should be fixed for decals/triplanar mapping.
+        v_tangent = vec3(1.0, 0.0, 0.0);
+      #else
+        v_tangent = normalize(vec3(c, 0.0, -s));
+      #endif
+      v_bitangent = cross(v_normal, v_tangent);
     #endif
 
     #if USE_SPECULAR_MAP