diff --git a/files/shaders/compatibility/terrain.frag b/files/shaders/compatibility/terrain.frag
index 9d89217f35..48183c0a92 100644
--- a/files/shaders/compatibility/terrain.frag
+++ b/files/shaders/compatibility/terrain.frag
@@ -49,7 +49,7 @@ void main()
     vec2 adjustedUV = (gl_TextureMatrix[0] * vec4(uv, 0.0, 1.0)).xy;
 
 #if @parallax
-    adjustedUV += getParallaxOffset(transpose(normalToViewMatrix) * normalize(-passViewPos), texture2D(normalMap, adjustedUV).a, 1.f);
+    adjustedUV += getParallaxOffset(transpose(normalToViewMatrix) * normalize(-passViewPos), texture2D(normalMap, adjustedUV).a, -1.0f);
 #endif
     vec4 diffuseTex = texture2D(diffuseMap, adjustedUV);
     gl_FragData[0] = vec4(diffuseTex.xyz, 1.0);
diff --git a/files/shaders/compatibility/terrain.vert b/files/shaders/compatibility/terrain.vert
index cbfb7769ba..40d69ff35d 100644
--- a/files/shaders/compatibility/terrain.vert
+++ b/files/shaders/compatibility/terrain.vert
@@ -46,8 +46,8 @@ void main(void)
     normalToViewMatrix = gl_NormalMatrix;
 
 #if @normalMap
-    mat3 tbnMatrix = generateTangentSpace(vec4(1.0, 0.0, 0.0, 1.0), passNormal);
-    tbnMatrix[0] = normalize(cross(tbnMatrix[2], tbnMatrix[1])); // note, now we need to re-cross to derive tangent again because it wasn't orthonormal
+    mat3 tbnMatrix = generateTangentSpace(vec4(1.0, 0.0, 0.0, -1.0), passNormal);
+    tbnMatrix[0] = -normalize(cross(tbnMatrix[2], tbnMatrix[1])); // our original tangent was not at a 90 degree angle to the normal, so we need to rederive it
     normalToViewMatrix *= tbnMatrix;
 #endif