diff --git a/fir2.c b/fir2.c
index adcf30a..f2aa6e5 100644
--- a/fir2.c
+++ b/fir2.c
@@ -6,7 +6,7 @@
 
 /* This needs to be a power of two for the bitmask optimizations to work */
 /* If a non power of two length is desired, change to modulo */
-#define FIR_LEN (1u << 5)
+#define FIR_LEN (1u << 5) // = 32
 _Static_assert((FIR_LEN & (FIR_LEN - 1u)) == 0, "FIR_LEN must be a power of two");
 
 typedef struct {