diff --git a/inc/qcbor/UsefulBuf.h b/inc/qcbor/UsefulBuf.h
index a8da83b..16a53d3 100644
--- a/inc/qcbor/UsefulBuf.h
+++ b/inc/qcbor/UsefulBuf.h
@@ -134,7 +134,7 @@
  These #define config options affect the inline implementation of
  UsefulOutBuf_InsertUint64() and UsefulInputBuf_GetUint64().  They
  also affect the 16-, 32-bit, float and double versions of these
- instructions. Since they are inline, they size effect is not in the
+ instructions. Since they are inline, the size effect is not in the
  UsefulBuf object code, but in the calling code.
 
  Summary: