diff --git a/drivers/include/ccs811.h b/drivers/include/ccs811.h
index 2421055489..f123cb76da 100644
--- a/drivers/include/ccs811.h
+++ b/drivers/include/ccs811.h
@@ -200,7 +200,7 @@ int ccs811_read_ntc (const ccs811_t *dev, uint32_t r_ref, uint32_t *r_ntc);
  * @brief   Data-ready status function
  *
  * The function reads the status register and returns CSS811_OK when new
- * data are available. The function is usefull for polling the sensor.
+ * data are available. The function is useful for polling the sensor.
  *
  * @param[in]   dev     Device descriptor of CCS811 device to read from
  *
diff --git a/sys/include/hashes/sha256.h b/sys/include/hashes/sha256.h
index 0e7b1fcfb5..69e9afb940 100644
--- a/sys/include/hashes/sha256.h
+++ b/sys/include/hashes/sha256.h
@@ -124,7 +124,7 @@ void sha256_final(sha256_context_t *ctx, void *digest);
 
 /**
  * @brief A wrapper function to simplify the generation of a hash, this is
- * usefull for generating sha256 for one buffer
+ * useful for generating sha256 for one buffer
  *
  * @param[in] data   pointer to the buffer to generate hash from
  * @param[in] len    length of the buffer
diff --git a/sys/include/hashes/sha3.h b/sys/include/hashes/sha3.h
index bc1b9e2d7c..927d88fd1b 100644
--- a/sys/include/hashes/sha3.h
+++ b/sys/include/hashes/sha3.h
@@ -154,7 +154,7 @@ void sha3_512_final(keccak_state_t *ctx, void *digest);
 
 /**
  * @brief A wrapper function to simplify the generation of a hash, this is
- * usefull for generating SHA-3-256 from one buffer
+ * useful for generating SHA-3-256 from one buffer
  *
  * @param[in] data     pointer to the buffer to generate hash from
  * @param[in] len      length of the buffer
@@ -165,7 +165,7 @@ void sha3_256(void *digest, const void *data, size_t len);
 
 /**
  * @brief A wrapper function to simplify the generation of a hash, this is
- * usefull for generating SHA-3-384 from one buffer
+ * useful for generating SHA-3-384 from one buffer
  *
  * @param[in] data     pointer to the buffer to generate hash from
  * @param[in] len      length of the buffer
@@ -176,7 +176,7 @@ void sha3_384(void *digest, const void *data, size_t len);
 
 /**
  * @brief A wrapper function to simplify the generation of a hash, this is
- * usefull for generating SHA-3-512 from one buffer
+ * useful for generating SHA-3-512 from one buffer
  *
  * @param[in] data     pointer to the buffer to generate hash from
  * @param[in] len      length of the buffer