diff --git a/lib/array_list.h b/lib/array_list.h
index 6c64f92..aebce28 100644
--- a/lib/array_list.h
+++ b/lib/array_list.h
@@ -4,6 +4,8 @@
 #include <stdbool.h>
 #include <stdlib.h>
 
+#include "types.h"
+
 #define ARRAY_LIST_INITIAL_CAPACITY 10
 
 /**
diff --git a/lib/character.h b/lib/character.h
index faee9bd..2046f47 100644
--- a/lib/character.h
+++ b/lib/character.h
@@ -5,6 +5,7 @@
 #include <stdlib.h>
 
 #include "string.h"
+#include "types.h"
 
 /**
  * @brief Append a character to a string, assuming string points to an array
diff --git a/lib/convert.h b/lib/convert.h
index 3521e95..a61b328 100644
--- a/lib/convert.h
+++ b/lib/convert.h
@@ -8,6 +8,7 @@
 #include "mathematics.h"
 #include "stdbool.h"
 #include "string.h"
+#include "types.h"
 
 /**
  * @brief Convert a character to a string.
diff --git a/lib/dictionary.h b/lib/dictionary.h
index 16ed4c0..d1450f5 100644
--- a/lib/dictionary.h
+++ b/lib/dictionary.h
@@ -5,6 +5,7 @@
 #include <stdlib.h>
 
 #include "string.h"
+#include "types.h"
 
 #define DICTIONARY_INITIAL_CAPACITY 10
 
diff --git a/lib/filesystem.h b/lib/filesystem.h
index d519ba8..5814619 100644
--- a/lib/filesystem.h
+++ b/lib/filesystem.h
@@ -6,14 +6,12 @@
 #include <fcntl.h>
 #include <pwd.h>
 #include <stdbool.h>
-#include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <unistd.h>
 
 #include "string.h"
-
-typedef uint8_t byte_t;
+#include "types.h"
 
 /**
  * @brief Read the content of a file.
diff --git a/lib/linked_list.h b/lib/linked_list.h
index ff20024..99f2100 100644
--- a/lib/linked_list.h
+++ b/lib/linked_list.h
@@ -5,6 +5,7 @@
 #include <stdlib.h>
 
 #include "stack.h"
+#include "types.h"
 
 /**
  * @brief Linked list data structure.
diff --git a/lib/mathematics.h b/lib/mathematics.h
index cc426fd..31166ed 100644
--- a/lib/mathematics.h
+++ b/lib/mathematics.h
@@ -5,6 +5,8 @@
 
 #include <stdbool.h>
 
+#include "types.h"
+
 /**
  * @brief Verify that 2 numbers are equal.
  *
diff --git a/lib/queue.h b/lib/queue.h
index 288fb17..123c8a3 100644
--- a/lib/queue.h
+++ b/lib/queue.h
@@ -4,6 +4,8 @@
 #include <stdio.h>
 #include <stdlib.h>
 
+#include "types.h"
+
 /**
  * @brief Queue structure => FIFO (First In First Out).
  * @since v1.0.0
diff --git a/lib/stack.h b/lib/stack.h
index 3333d43..b0eb2b5 100644
--- a/lib/stack.h
+++ b/lib/stack.h
@@ -4,6 +4,8 @@
 #include <stdio.h>
 #include <stdlib.h>
 
+#include "types.h"
+
 /**
  * @brief Stack structure => LIFO (Last In First Out).
  * @since v1.0.0
diff --git a/lib/string.h b/lib/string.h
index dac4e4f..d5cb44a 100644
--- a/lib/string.h
+++ b/lib/string.h
@@ -8,8 +8,7 @@
 #include "character.h"
 #include "convert.h"
 #include "dictionary.h"
-
-typedef char* string_t;
+#include "types.h"
 
 /**
  * @brief Return the length of a string (excluding '\0').
diff --git a/lib/terminal.h b/lib/terminal.h
index a2a5091..cde227e 100644
--- a/lib/terminal.h
+++ b/lib/terminal.h
@@ -11,6 +11,7 @@
 #include "linked_list.h"
 #include "queue.h"
 #include "stack.h"
+#include "types.h"
 
 /**
  * @brief Read a line from stdin.
diff --git a/lib/types.h b/lib/types.h
new file mode 100644
index 0000000..92eacf4
--- /dev/null
+++ b/lib/types.h
@@ -0,0 +1,10 @@
+#ifndef __TYPES__
+#define __TYPES__
+
+#include <stdint.h>
+
+typedef uint8_t byte_t;
+
+typedef char* string_t;
+
+#endif
diff --git a/libcproject.h b/libcproject.h
index 3a81352..be5758a 100644
--- a/libcproject.h
+++ b/libcproject.h
@@ -12,6 +12,7 @@
 #include "lib/stack.h"
 #include "lib/string.h"
 #include "lib/terminal.h"
+#include "lib/types.h"
 #include "version.h"
 
 #endif