diff --git a/src/ip.h b/src/ip.h
index cf238ff..e33a7e3 100644
--- a/src/ip.h
+++ b/src/ip.h
@@ -10,16 +10,17 @@ struct ip_common {
     uint16_t size;
 };
 
-_pure_
-static inline uint8_t ip_get_version (const uint8_t *data, size_t size)
+_pure_ static inline uint8_t
+ip_get_version(const uint8_t *data, size_t size)
 {
-    if (size<20)
+    if (size < 20)
         return 0;
 
-    return data[0]>>4;
+    return data[0] >> 4;
 }
 
-static inline int ip_get_common (struct ip_common *ic, const uint8_t *data, size_t size)
+static inline int
+ip_get_common(struct ip_common *ic, const uint8_t *data, size_t size)
 {
     ic->version = ip_get_version(data, size);
 
@@ -27,14 +28,14 @@ static inline int ip_get_common (struct ip_common *ic, const uint8_t *data, size
     case 4:
         ic->tc = data[1];
         ic->proto = data[9];
-        ic->hdr_size = (data[0]&0xF)<<2;
-        ic->size = ((data[2]<<8)|data[3]);
+        ic->hdr_size = (data[0] & 0xF) << 2;
+        ic->size = ((data[2] << 8) | data[3]);
         return 0;
     case 6:
-        ic->tc = ((data[0]&0xF)<<4)|(data[1]>>4);
+        ic->tc = ((data[0] & 0xF) << 4) | (data[1] >> 4);
         ic->proto = data[6];
         ic->hdr_size = 40;
-        ic->size = ((data[4]<<8)|data[5])+40;
+        ic->size = ((data[4] << 8) | data[5]) + 40;
         return 0;
     }
 
diff --git a/src/main.c b/src/main.c
index 534780d..b5c097c 100644
--- a/src/main.c
+++ b/src/main.c
@@ -386,8 +386,8 @@ main(int argc, char **argv)
             size_t size = 0;
 
             while (sizeof(buf) - size >= gt.mtu) {
-                const ssize_t r = tun_read(tun_fd, &buf[size],
-                                           sizeof(buf) - size);
+                const int r = tun_read(tun_fd, &buf[size],
+                                       sizeof(buf) - size);
 
                 if (r <= 0 || r > gt.mtu)
                     break;
diff --git a/src/str.h b/src/str.h
index 1828913..effd96b 100644
--- a/src/str.h
+++ b/src/str.h
@@ -2,14 +2,15 @@
 
 #include "common.h"
 
-static inline size_t str_cpy (char *restrict dst, const char *restrict src, size_t len)
+static inline size_t
+str_cpy(char *restrict dst, const char *restrict src, size_t len)
 {
     if (!dst || !src)
         return 0;
 
     size_t i;
 
-    for (i=0; i<len && src[i]; i++)
+    for (i = 0; i < len && src[i]; i++)
         dst[i] = src[i];
 
     dst[i] = 0;
@@ -17,29 +18,29 @@ static inline size_t str_cpy (char *restrict dst, const char *restrict src, size
     return i;
 }
 
-_pure_
-static inline int str_empty (const char *restrict str)
+_pure_ static inline int
+str_empty(const char *restrict str)
 {
     return !str || !str[0];
 }
 
-_pure_
-static inline size_t str_cmp (const char *restrict sa, const char *restrict sb)
+_pure_ static inline size_t
+str_cmp(const char *restrict sa, const char *restrict sb)
 {
     if (!sa || !sb)
         return 1;
 
     size_t i = 0;
 
-    while (sa[i]==sb[i])
+    while (sa[i] == sb[i])
         if (!sa[i++])
             return 0;
 
-    return i+1;
+    return i + 1;
 }
 
-_pure_
-static inline size_t str_len (const char *restrict str)
+_pure_ static inline size_t
+str_len(const char *restrict str)
 {
     if (!str)
         return 0;
@@ -47,11 +48,12 @@ static inline size_t str_len (const char *restrict str)
     return strlen(str);
 }
 
-static inline char *str_cat (const char **strs, size_t count)
+static inline char *
+str_cat(const char **strs, size_t count)
 {
     size_t size = 1;
 
-    for (size_t i=0; i<count; i++)
+    for (size_t i = 0; i < count; i++)
         size += str_len(strs[i]);
 
     char *str = malloc(size);
@@ -61,7 +63,7 @@ static inline char *str_cat (const char **strs, size_t count)
 
     char *p = str;
 
-    for (size_t i=0; i<count; i++) {
+    for (size_t i = 0; i < count; i++) {
         size_t len = str_len(strs[i]);
         memcpy(p, strs[i], len);
         p += len;
diff --git a/src/tun.c b/src/tun.c
index bfe58b1..75e905b 100644
--- a/src/tun.c
+++ b/src/tun.c
@@ -158,7 +158,7 @@ tun_create(char *dev_name, char **ret_name)
     return fd;
 }
 
-ssize_t
+int
 tun_read(int fd, void *data, size_t size)
 {
     if (!size)
@@ -192,7 +192,7 @@ tun_read(int fd, void *data, size_t size)
 #endif
 }
 
-ssize_t
+int
 tun_write(int fd, const void *data, size_t size)
 {
     if (!size)
diff --git a/src/tun.h b/src/tun.h
index bb5e8cb..f99d92a 100644
--- a/src/tun.h
+++ b/src/tun.h
@@ -1,8 +1,6 @@
 #pragma once
 
-#include <unistd.h>
-
-int     tun_create  (char *, char **);
-ssize_t tun_read    (int, void *, size_t);
-ssize_t tun_write   (int, const void *, size_t);
-int     tun_set_mtu (char *, int);
+int tun_create  (char *, char **);
+int tun_read    (int, void *, size_t);
+int tun_write   (int, const void *, size_t);
+int tun_set_mtu (char *, int);