diff --git a/crc32.c b/crc32.c
index ed39710..f6cd52f 100644
--- a/crc32.c
+++ b/crc32.c
@@ -530,7 +530,8 @@
 }
 
 /*
-  Return x^(n+k) modulo p(x). Requires that x2n_table[] has been initialized.
+  Return x^(n * 2^k) modulo p(x). Requires that x2n_table[] has been
+  initialized.
  */
 local z_crc_t x2nmodp(n, k)
     z_off64_t n;