diff --git a/lib/character.h b/lib/character.h
index 2046f47..7700c1d 100644
--- a/lib/character.h
+++ b/lib/character.h
@@ -31,7 +31,6 @@ void character_append_at(string_t string_value, const char character, const size
  * @brief Converts the character to uppercase.
  *
  * @param character
- * @return const char
  * @since v1.0.0
  */
 char character_to_upper(const char character);
@@ -40,7 +39,6 @@ char character_to_upper(const char character);
  * @brief Converts the character to lowercase.
  *
  * @param character
- * @return const char
  * @since v1.0.0
  */
 char character_to_lower(const char character);
@@ -60,7 +58,6 @@ bool character_get_is_digit(const char character);
  * Return 0 if the character is not a letter.
  *
  * @param character
- * @return char
  * @since v1.0.0
  */
 unsigned char character_get_alphabet_position(const char character);
diff --git a/lib/filesystem.h b/lib/filesystem.h
index 5814619..415e416 100644
--- a/lib/filesystem.h
+++ b/lib/filesystem.h
@@ -19,7 +19,6 @@
  * @param path
  * @param file_content
  * @param file_size
- * @return int
  * @retval -1 if the file does not exist or if there is an error.
  * @retval 0 for success.
  * @since v1.0.0
@@ -32,7 +31,6 @@ int filesystem_read(string_t path, byte_t **file_content, off_t *file_size);
  * @param path
  * @param file_content
  * @param file_size
- * @return int
  * @retval -1 if there is an error.
  * @retval 0 for success.
  * @since v1.0.0
diff --git a/lib/mathematics.h b/lib/mathematics.h
index 31166ed..4482ce9 100644
--- a/lib/mathematics.h
+++ b/lib/mathematics.h
@@ -20,7 +20,6 @@ bool mathematics_equals(const float number1, const float number2);
  * @brief Get the absolute value of a number.
  *
  * @param number
- * @return unsigned long long
  * @since v1.0.0
  */
 unsigned long long mathematics_absolute_value(const long long number);
@@ -30,7 +29,6 @@ unsigned long long mathematics_absolute_value(const long long number);
  *
  * @param base
  * @param exponent
- * @return unsigned long long
  * @since v1.0.0
  */
 unsigned long long mathematics_pow(unsigned long long base, unsigned long long exponent);
@@ -40,7 +38,6 @@ unsigned long long mathematics_pow(unsigned long long base, unsigned long long e
  *
  * @param number
  * @param nth_root
- * @return float
  * @since v1.0.0
  */
 float mathematics_root(float number, unsigned int nth_root);
@@ -49,7 +46,6 @@ float mathematics_root(float number, unsigned int nth_root);
  * @brief Calculates the square root of a number using Heron's method.
  *
  * @param number
- * @return float
  * @since v1.0.0
  */
 float mathematics_square_root(float number);
@@ -58,7 +54,6 @@ float mathematics_square_root(float number);
  * @brief Calculates the factorial of a number.
  *
  * @param number
- * @return unsigned long long
  * @since v1.0.0
  */
 unsigned long long mathematics_factorial(unsigned long long number);
diff --git a/lib/string.h b/lib/string.h
index d5cb44a..5c3041f 100644
--- a/lib/string.h
+++ b/lib/string.h
@@ -14,7 +14,6 @@
  * @brief Return the length of a string (excluding '\0').
  *
  * @param string
- * @return size_t
  * @since v1.0.0
  */
 size_t string_get_length(const string_t string_value);
@@ -90,7 +89,6 @@ string_t string_capitalize(string_t string_value);
  *
  * @param string
  * @param character
- * @return size_t
  * @since v1.0.0
  */
 size_t string_total_occurrences_of_character(string_t string_value, char character);