diff --git a/include/mbedtls/hmac_drbg.h b/include/mbedtls/hmac_drbg.h
index 146367b..c81df8c 100644
--- a/include/mbedtls/hmac_drbg.h
+++ b/include/mbedtls/hmac_drbg.h
@@ -76,7 +76,7 @@
  */
 typedef struct mbedtls_hmac_drbg_context
 {
-    /* Working state: the key K is not stored explicitely,
+    /* Working state: the key K is not stored explicitly,
      * but is implied by the HMAC context */
     mbedtls_md_context_t md_ctx;                    /*!< HMAC context (inc. K)  */
     unsigned char V[MBEDTLS_MD_MAX_SIZE];  /*!< V in the spec          */