diff --git a/shaders/graph.glsl b/shaders/graph.glsl
index 846fb89..1906195 100644
--- a/shaders/graph.glsl
+++ b/shaders/graph.glsl
@@ -22,6 +22,8 @@
 #define ANTI_ALIAS 0
 /* outline color */
 #define OUTLINE #262626
+/* 1 to join the two channels together in the middle, 0 to clamp both down to zero */
+#define JOIN_CHANNELS 0
 /* 1 to invert (vertically), 0 otherwise */
 #define INVERT 0
 
diff --git a/shaders/graph/1.frag b/shaders/graph/1.frag
index afdf2c4..04839d8 100644
--- a/shaders/graph/1.frag
+++ b/shaders/graph/1.frag
@@ -91,8 +91,12 @@ float get_line_height(in sampler1D tex, float idx) {
     /* clamp far ends of the screen down to make the ends of the graph smoother */
 
     float fact = clamp((abs((screen.x / 2) - gl_FragCoord.x) / screen.x) * 48, 0.0F, 1.0F);
+    #if JOIN_CHANNELS > 0
     fact = pow(fact, 1.8);  /* To avoid spikes */
     s = fact * s + (1 - fact) * middle;
+    #else
+    s *= fact;
+    #endif
 
     s *= clamp((min(gl_FragCoord.x, screen.x - gl_FragCoord.x) / screen.x) * 48, 0.0F, 1.0F);