diff --git a/src/strbuff_prefixs.c b/src/strbuff_prefixs.c
index eab0e3f..884d5bc 100644
--- a/src/strbuff_prefixs.c
+++ b/src/strbuff_prefixs.c
@@ -15,24 +15,35 @@
  *
  * @details If dest or src buffer pointer is null, then the function returns 0.
  */
-// unsigned long strbuff_prefixs(const strbuff *dest, const char *src_str)
-// {
-//     strbuff_check_not_null(dest, return 0);
-//     strbuff_check_not_null(src_str, return 0);
+unsigned long strbuff_prefixs(const strbuff *dest, const char *src_str)
+{
+    strbuff_check_not_null(dest, return 0);
+    strbuff_check_not_null(src_str, return 0);
 
-//     size_t _dest_len = strbuff_len(dest);
+    size_t _dest_len = strbuff_len(dest);
 
-//     const char *s;
+    size_t      _src_len = 0;
+    const char *s;
 
-//     for (s = src_str; *s; s++) {
-//         if (_dest_len == (strbuff_capacity(dest) - 1)) {
-//             break;
-//         }
-//         *(dest->str + _dest_len) = *s;
-//         _dest_len++;
-//     }
+    /* Compute the size of the string to add */
+    for (s = src_str; *s; s++) {
+        if (_src_len == (strbuff_capacity(dest) - 1)) {
+            break;
+        }
+        _src_len++;
+    }
 
-//     *(dest->str + _dest_len) = 0;
+    /* If dest string buffer is not empty, move its content */
+    if (_dest_len != 0) {
+        /* If the two contents do not fit, the end will be lost */
+        if (_dest_len + _src_len >= strbuff_capacity(dest)) {
+            _dest_len = strbuff_capacity(dest) - 1 - _src_len;
+        }
+        memmove(dest->str + _src_len, dest->str, _src_len);
+    }
 
-//     return (size_t)(s - src_str);
-// }
+    /* Copy the new begining of dest string buffer */
+    memcpy(dest->str, src_str, _src_len);
+
+    return _src_len;
+}
diff --git a/test/test_strbuff.c b/test/test_strbuff.c
index 3a86250..265e63e 100644
--- a/test/test_strbuff.c
+++ b/test/test_strbuff.c
@@ -128,6 +128,7 @@ int main(void)
         test_strbuff_find();
         test_strbuff_len();
         test_strbuff_prefixb();
+        test_strbuff_prefixs();
         test_strbuff_printc();
         test_strbuff_prints();
         test_strbuff_revert();
diff --git a/test/test_strbuff.h b/test/test_strbuff.h
index 7650245..0b70a30 100644
--- a/test/test_strbuff.h
+++ b/test/test_strbuff.h
@@ -77,6 +77,7 @@ void test_strbuff_end_with(void);
 void test_strbuff_find(void);
 void test_strbuff_len(void);
 void test_strbuff_prefixb(void);
+void test_strbuff_prefixs(void);
 // void test_strbuff_printb(void);
 void test_strbuff_printc(void);
 // void test_strbuff_printf(void);
diff --git a/test/test_strbuff_prefixs.c b/test/test_strbuff_prefixs.c
new file mode 100644
index 0000000..f5396e8
--- /dev/null
+++ b/test/test_strbuff_prefixs.c
@@ -0,0 +1,44 @@
+// ==========================================
+//   String Buffer Project - A safe string library for C
+//   Copyright (c) 2023 Alex Fabre
+//   [Released under MIT License. Please refer to license.txt for details]
+// ==========================================
+
+#include "test_strbuff.h"
+
+static void test_strbuff_prefixs_buffer_on_non_empty_buffer(void)
+{
+    rand_string(buffer1.str, strbuff_capacity(&buffer1) / 3);
+
+    char tmp_buffer[TEST_BUFFER_SIZE];
+    memcpy(tmp_buffer, buffer1.str, strbuff_capacity(&buffer1));
+
+    char tmp_buffer2[TEST_BUFFER_SIZE / 3];
+
+    rand_string(tmp_buffer2, sizeof(tmp_buffer2));
+
+    size_t n1 = strlen(buffer1.str);
+    size_t n2 = strlen(tmp_buffer2);
+
+    TEST_ASSERT_EQUAL(n2, strbuff_prefix(&buffer1, tmp_buffer2));
+    TEST_ASSERT_EQUAL((n1 + n2), strbuff_len(&buffer1));
+    TEST_ASSERT_EQUAL_STRING_LEN(tmp_buffer2, buffer1.str, n2);
+    TEST_ASSERT_EQUAL_STRING_LEN(tmp_buffer, buffer1.str + n2, n1);
+}
+
+static void test_strbuff_prefixs_buffer_on_filled_buffer(void)
+{
+    rand_string_fixed_length(buffer1.str, strbuff_capacity(&buffer1), strbuff_capacity(&buffer1) - 1);
+
+    char tmp_buffer2[] = "Hello";
+
+    TEST_ASSERT_EQUAL(5, strbuff_prefix(&buffer1, tmp_buffer2));
+    TEST_ASSERT_EQUAL(strbuff_capacity(&buffer1) - 1, strbuff_len(&buffer1));
+    TEST_ASSERT_EQUAL_STRING_LEN("Hello", buffer1.str, 5);
+}
+
+void test_strbuff_prefixs(void)
+{
+    RUN_TEST(test_strbuff_prefixs_buffer_on_non_empty_buffer);
+    RUN_TEST(test_strbuff_prefixs_buffer_on_filled_buffer);
+}