diff --git a/internal/shaderir/glsl.go b/internal/shaderir/glsl.go
index e6d08fc34..663722dc2 100644
--- a/internal/shaderir/glsl.go
+++ b/internal/shaderir/glsl.go
@@ -219,8 +219,10 @@ func (p *Program) glslBlock(b *Block, level int, localVarIndex int) []string {
 					return fmt.Sprintf("V%d", idx)
 				case idx == nv:
 					return "gl_FragCoord"
+				case idx == nv+1:
+					return "gl_FragColor"
 				default:
-					return fmt.Sprintf("l%d", idx-(nv+1))
+					return fmt.Sprintf("l%d", idx-(nv+2))
 				}
 			default:
 				return fmt.Sprintf("l%d", idx)
diff --git a/internal/shaderir/ir_test.go b/internal/shaderir/ir_test.go
index 99f6efeed..7f7ed214d 100644
--- a/internal/shaderir/ir_test.go
+++ b/internal/shaderir/ir_test.go
@@ -757,9 +757,9 @@ void main(void) {
 	vec2 l0;
 	vec4 l1;
 	float l2;
-	l2 = V0;
-	l0 = V1;
-	l1 = gl_FragCoord;
+	l1 = V0;
+	gl_FragColor = V1;
+	l0 = gl_FragCoord;
 }`,
 		},
 	}