diff --git a/CHANGELOG.md b/CHANGELOG.md
index a131fe05d..86bfcaf5a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,6 +3,7 @@
 
     Bug #2987: Editor: some chance and AI data fields can overflow
     Bug #3623: Fix HiDPI on Windows
+    Bug #3733: Normal maps are inverted on mirrored UVs
     Bug #4329: Removed birthsign abilities are restored after reloading the save
     Bug #4383: Bow model obscures crosshair when arrow is drawn
     Bug #4411: Reloading a saved game while falling prevents damage in some cases
diff --git a/files/shaders/objects_fragment.glsl b/files/shaders/objects_fragment.glsl
index ed1322609..731e8cbd8 100644
--- a/files/shaders/objects_fragment.glsl
+++ b/files/shaders/objects_fragment.glsl
@@ -68,7 +68,7 @@ void main()
 
     vec3 normalizedNormal = normalize(passNormal);
     vec3 normalizedTangent = normalize(passTangent.xyz);
-    vec3 binormal = cross(normalizedTangent, normalizedNormal);
+    vec3 binormal = cross(normalizedTangent, normalizedNormal) * passTangent.w;
     mat3 tbnTranspose = mat3(normalizedTangent, binormal, normalizedNormal);
 
     vec3 viewNormal = gl_NormalMatrix * normalize(tbnTranspose * (normalTex.xyz * 2.0 - 1.0));