diff --git a/library/debug.c b/library/debug.c
index 6114a46..78ce9ce 100644
--- a/library/debug.c
+++ b/library/debug.c
@@ -107,7 +107,7 @@
     /*
      * With non-blocking I/O and examples that just retry immediately,
      * the logs would be quickly flooded with WANT_READ, so ignore that.
-     * Don't ignore WANT_WRITE however, since is is usually rare.
+     * Don't ignore WANT_WRITE however, since it is usually rare.
      */
     if( ret == MBEDTLS_ERR_SSL_WANT_READ )
         return;