diff --git a/servers/rendering/rasterizer_rd/shaders/tonemap.glsl b/servers/rendering/rasterizer_rd/shaders/tonemap.glsl
index a464048ebdc..e7b46a07068 100644
--- a/servers/rendering/rasterizer_rd/shaders/tonemap.glsl
+++ b/servers/rendering/rasterizer_rd/shaders/tonemap.glsl
@@ -157,6 +157,10 @@ vec3 tonemap_aces(vec3 color, float white) {
 }
 
 vec3 tonemap_reinhard(vec3 color, float white) {
+	// Ensure color values are positive.
+	// They can be negative in the case of negative lights, which leads to undesired behavior.
+	color = max(vec3(0.0), color);
+
 	return (white * color + color) / (color * white + white);
 }