diff --git a/glava.c b/glava.c
index f7ab563..9882ca8 100644
--- a/glava.c
+++ b/glava.c
@@ -182,7 +182,7 @@ static const char* help_str =
     "                           appropriate backend will be used for the underlying windowing\n"
     "                           system.\n"
     "-a, --audio=BACKEND      specifies an audio input backend to use.\n"
-    "-p, --pipe=[BIND[:TYPE]] binds value(s) to be read from stdin. The input my be read using\n"
+    "-p, --pipe[=BIND[:TYPE]] binds value(s) to be read from stdin. The input my be read using\n"
     "                           `@name` or `@name:default` syntax within shader sources.\n"
     "                           A stream of inputs (each overriding the previous) must be\n"
     "                           assigned with the `name = value` syntax and separated by\n"
diff --git a/shaders/radial.glsl b/shaders/radial.glsl
index 4689be6..c454202 100644
--- a/shaders/radial.glsl
+++ b/shaders/radial.glsl
@@ -19,7 +19,7 @@
 #define COLOR (#cc3333 * ((d / 40) + 1))
 /* Angle (in radians) for how much to rotate the visualizer */
 #define ROTATE (PI / 2)
-/* Whether to switch left/right audio buffers */
+/* Whether to swap left/right audio buffers, set to 1 to enable */
 #define INVERT 0
 /* Aliasing factors. Higher values mean more defined and jagged lines.
    Note: aliasing does not have a notable impact on performance, but requires
diff --git a/shaders/radial/1.frag b/shaders/radial/1.frag
index 641c3ec..9cc0b46 100644
--- a/shaders/radial/1.frag
+++ b/shaders/radial/1.frag
@@ -64,7 +64,7 @@ void main() {
             float dir = mod(abs(idx), TWOPI);          /* absolute position, [0, 2pi) */
             if (dir > PI)
                 idx = -sign(idx) * (TWOPI - dir);      /* Re-correct position values to [-pi, pi) */
-            if (INVERT > 0)
+            #if INVERT == 0
                 idx = -idx;                            /* Invert if needed */
             float pos = int(abs(idx) / section) / float(NBARS / 2);        /* bar position, [0, 1) */
             #define smooth_f(tex) smooth_audio(tex, audio_sz, pos)         /* smooth function format */