diff --git a/cpu/kinetis_common/dist/calc_spi_scalers/calc_spi_scalers.c b/cpu/kinetis_common/dist/calc_spi_scalers/calc_spi_scalers.c
index a80045b46..1d98e9017 100644
--- a/cpu/kinetis_common/dist/calc_spi_scalers/calc_spi_scalers.c
+++ b/cpu/kinetis_common/dist/calc_spi_scalers/calc_spi_scalers.c
@@ -183,7 +183,7 @@ int main(int argc, char **argv)
         return 1;
     }
 
-    modclk = (uint32_t)atoi(argv[1]);
+    modclk = atoi(argv[1]);
     if (modclk == 0) {
         printf("error: invalid input value\n");
         return 1;
diff --git a/dist/tools/coccinelle/warn/remove_atoi_cast.cocci b/dist/tools/coccinelle/warn/remove_atoi_cast.cocci
new file mode 100644
index 000000000..e2115dd92
--- /dev/null
+++ b/dist/tools/coccinelle/warn/remove_atoi_cast.cocci
@@ -0,0 +1,11 @@
+// removes not needed casts like "e = (uint16_t) atoi(e2)"
+
+@@
+expression e;
+expression e2;
+type t;
+@@
+
+e =
+- (t)
+atoi(e2)
diff --git a/examples/dtls-echo/dtls-client.c b/examples/dtls-echo/dtls-client.c
index 27cbfd2cb..b5dcbce24 100644
--- a/examples/dtls-echo/dtls-client.c
+++ b/examples/dtls-echo/dtls-client.c
@@ -509,7 +509,7 @@ int udp_client_cmd(int argc, char **argv)
         return 1;
     }
     else if (argc > 3) {
-        delay = (uint32_t)atoi(argv[3]);
+        delay = atoi(argv[3]);
     }
     client_send(argv[1], argv[2],  delay);
 
diff --git a/examples/emcute/main.c b/examples/emcute/main.c
index 9184a8c10..520cae9bf 100644
--- a/examples/emcute/main.c
+++ b/examples/emcute/main.c
@@ -89,7 +89,7 @@ static int cmd_con(int argc, char **argv)
     }
 
     if (argc >= 3) {
-        gw.port = (uint16_t)atoi(argv[2]);
+        gw.port = atoi(argv[2]);
     }
     if (argc >= 5) {
         topic = argv[3];
diff --git a/examples/gcoap/gcoap_cli.c b/examples/gcoap/gcoap_cli.c
index 4e03f280e..8542bcab3 100644
--- a/examples/gcoap/gcoap_cli.c
+++ b/examples/gcoap/gcoap_cli.c
@@ -110,7 +110,7 @@ static size_t _send(uint8_t *buf, size_t len, char *addr_str, char *port_str)
     memcpy(&remote.addr.ipv6[0], &addr.u8[0], sizeof(addr.u8));
 
     /* parse port */
-    remote.port = (uint16_t)atoi(port_str);
+    remote.port = atoi(port_str);
     if (remote.port == 0) {
         puts("gcoap_cli: unable to parse destination port");
         return 0;
diff --git a/examples/gnrc_networking/udp.c b/examples/gnrc_networking/udp.c
index b3feccf97..fcfb54e87 100644
--- a/examples/gnrc_networking/udp.c
+++ b/examples/gnrc_networking/udp.c
@@ -44,7 +44,7 @@ static void send(char *addr_str, char *port_str, char *data, unsigned int num,
         return;
     }
     /* parse port */
-    port = (uint16_t)atoi(port_str);
+    port = atoi(port_str);
     if (port == 0) {
         puts("Error: unable to parse destination port");
         return;
@@ -100,7 +100,7 @@ static void start_server(char *port_str)
         return;
     }
     /* parse port */
-    port = (uint16_t)atoi(port_str);
+    port = atoi(port_str);
     if (port == 0) {
         puts("Error: invalid port specified");
         return;
@@ -141,10 +141,10 @@ int udp_cmd(int argc, char **argv)
             return 1;
         }
         if (argc > 5) {
-            num = (uint32_t)atoi(argv[5]);
+            num = atoi(argv[5]);
         }
         if (argc > 6) {
-            delay = (uint32_t)atoi(argv[6]);
+            delay = atoi(argv[6]);
         }
         send(argv[2], argv[3], argv[4], num, delay);
     }
diff --git a/examples/posix_sockets/udp.c b/examples/posix_sockets/udp.c
index c386c1e27..ecf30bf6e 100644
--- a/examples/posix_sockets/udp.c
+++ b/examples/posix_sockets/udp.c
@@ -45,7 +45,7 @@ static void *_server_thread(void *args)
     msg_init_queue(server_msg_queue, SERVER_MSG_QUEUE_SIZE);
     server_socket = socket(AF_INET6, SOCK_DGRAM, IPPROTO_UDP);
     /* parse port */
-    port = (uint16_t)atoi((char *)args);
+    port = atoi((char *)args);
     if (port == 0) {
         puts("Error: invalid port specified");
         return NULL;
@@ -99,7 +99,7 @@ static int udp_send(char *addr_str, char *port_str, char *data, unsigned int num
         return 1;
     }
     /* parse port */
-    port = (uint16_t)atoi(port_str);
+    port = atoi(port_str);
     dst.sin6_port = htons(port);
     src.sin6_port = htons(port);
     s = socket(AF_INET6, SOCK_DGRAM, IPPROTO_UDP);
@@ -155,10 +155,10 @@ int udp_cmd(int argc, char **argv)
             return 1;
         }
         if (argc > 5) {
-            num = (uint32_t)atoi(argv[5]);
+            num = atoi(argv[5]);
         }
         if (argc > 6) {
-            delay = (uint32_t)atoi(argv[6]);
+            delay = atoi(argv[6]);
         }
         return udp_send(argv[2], argv[3], argv[4], num, delay);
     }
diff --git a/sys/shell/commands/sc_gnrc_6ctx.c b/sys/shell/commands/sc_gnrc_6ctx.c
index 9a544986a..7c903948c 100644
--- a/sys/shell/commands/sc_gnrc_6ctx.c
+++ b/sys/shell/commands/sc_gnrc_6ctx.c
@@ -80,7 +80,7 @@ int _gnrc_6ctx_add(char *cmd_str, char *ctx_str, char *prefix_str, char *ltime_s
     char *addr_str, *prefix_len_str, *save_ptr;
     unsigned prefix_len;
     unsigned ltime;
-    unsigned ctx = (unsigned)atoi(ctx_str);
+    unsigned ctx = atoi(ctx_str);
     if (ctx >= GNRC_SIXLOWPAN_CTX_SIZE) {
         _usage(cmd_str);
         return 1;
@@ -95,7 +95,7 @@ int _gnrc_6ctx_add(char *cmd_str, char *ctx_str, char *prefix_str, char *ltime_s
         _usage(cmd_str);
         return 1;
     }
-    prefix_len = (unsigned)atoi(prefix_len_str);
+    prefix_len = atoi(prefix_len_str);
     if ((prefix_len - 1U) > 128U) {
         puts("ERROR: prefix_len < 1 || prefix_len > 128");
         return 1;
@@ -112,7 +112,7 @@ int _gnrc_6ctx_add(char *cmd_str, char *ctx_str, char *prefix_str, char *ltime_s
         puts("ERROR: can not add context");
         return 1;
     }
-    ltime = (unsigned)atoi(ltime_str);
+    ltime = atoi(ltime_str);
     if (gnrc_sixlowpan_ctx_update((uint8_t)ctx, &prefix, (uint8_t)prefix_len, ltime,
                                   true) == NULL) {
         puts("ERROR: can not add context");
@@ -126,7 +126,7 @@ int _gnrc_6ctx_add(char *cmd_str, char *ctx_str, char *prefix_str, char *ltime_s
 int _gnrc_6ctx_del(char *cmd_str, char *ctx_str)
 {
     gnrc_sixlowpan_ctx_t *ctx;
-    unsigned cid = (unsigned)atoi(ctx_str);
+    unsigned cid = atoi(ctx_str);
     if (cid >= GNRC_SIXLOWPAN_CTX_SIZE) {
         _usage(cmd_str);
         return 1;
diff --git a/sys/shell/commands/sc_gnrc_rpl.c b/sys/shell/commands/sc_gnrc_rpl.c
index a10b5f5ca..e9cdd8258 100644
--- a/sys/shell/commands/sc_gnrc_rpl.c
+++ b/sys/shell/commands/sc_gnrc_rpl.c
@@ -31,7 +31,7 @@
 
 int _gnrc_rpl_init(char *arg)
 {
-    kernel_pid_t iface_pid = (kernel_pid_t) atoi(arg);
+    kernel_pid_t iface_pid = atoi(arg);
     gnrc_ipv6_netif_t *entry = gnrc_ipv6_netif_get(iface_pid);
 
     if (entry == NULL) {
@@ -46,7 +46,7 @@ int _gnrc_rpl_init(char *arg)
 
 int _gnrc_rpl_dodag_root(char *arg1, char *arg2)
 {
-    uint8_t instance_id = (uint8_t) atoi(arg1);
+    uint8_t instance_id = atoi(arg1);
     ipv6_addr_t dodag_id;
 
     if (ipv6_addr_from_str(&dodag_id, arg2) == NULL) {
@@ -69,7 +69,7 @@ int _gnrc_rpl_dodag_root(char *arg1, char *arg2)
 #ifdef MODULE_GNRC_RPL_P2P
 int _gnrc_rpl_find(char *arg1, char *arg2)
 {
-    uint8_t instance_id = (uint8_t) atoi(arg1);
+    uint8_t instance_id = atoi(arg1);
     ipv6_addr_t dodag_id;
     ipv6_addr_t target;
 
@@ -97,7 +97,7 @@ int _gnrc_rpl_find(char *arg1, char *arg2)
 
 int _gnrc_rpl_instance_remove(char *arg1)
 {
-    uint8_t instance_id = (uint8_t) atoi(arg1);
+    uint8_t instance_id = atoi(arg1);
     gnrc_rpl_instance_t *inst;
 
     if ((inst = gnrc_rpl_instance_get(instance_id)) == NULL) {
@@ -116,7 +116,7 @@ int _gnrc_rpl_instance_remove(char *arg1)
 
 int _gnrc_rpl_trickle_reset(char *arg1)
 {
-    uint8_t instance_id = (uint8_t) atoi(arg1);
+    uint8_t instance_id = atoi(arg1);
     gnrc_rpl_instance_t *inst;
     char addr_str[IPV6_ADDR_MAX_STR_LEN];
 
@@ -135,7 +135,7 @@ int _gnrc_rpl_trickle_reset(char *arg1)
 
 int _gnrc_rpl_trickle_stop(char *arg1)
 {
-    uint8_t instance_id = (uint8_t) atoi(arg1);
+    uint8_t instance_id = atoi(arg1);
     gnrc_rpl_instance_t *inst;
     char addr_str[IPV6_ADDR_MAX_STR_LEN];
 
@@ -153,7 +153,7 @@ int _gnrc_rpl_trickle_stop(char *arg1)
 
 int _gnrc_rpl_trickle_start(char *arg1)
 {
-    uint8_t instance_id = (uint8_t) atoi(arg1);
+    uint8_t instance_id = atoi(arg1);
     gnrc_rpl_instance_t *inst;
     char addr_str[IPV6_ADDR_MAX_STR_LEN];
 
@@ -312,7 +312,7 @@ int _gnrc_rpl_dodag_show(void)
 
 int _gnrc_rpl_operation(bool leaf, char *arg1)
 {
-    uint8_t instance_id = (uint8_t) atoi(arg1);
+    uint8_t instance_id = atoi(arg1);
     gnrc_rpl_instance_t *inst;
 
     if ((inst = gnrc_rpl_instance_get(instance_id)) == NULL) {
@@ -334,7 +334,7 @@ int _gnrc_rpl_operation(bool leaf, char *arg1)
 #ifndef GNRC_RPL_WITHOUT_PIO
 int _gnrc_rpl_set_pio(char *inst_id, bool status)
 {
-    uint8_t instance_id = (uint8_t) atoi(inst_id);
+    uint8_t instance_id = atoi(inst_id);
     gnrc_rpl_instance_t *inst;
 
     if ((inst = gnrc_rpl_instance_get(instance_id)) == NULL) {
diff --git a/sys/shell/commands/sc_netif.c b/sys/shell/commands/sc_netif.c
index e3a254698..9a3f17fa3 100644
--- a/sys/shell/commands/sc_netif.c
+++ b/sys/shell/commands/sc_netif.c
@@ -560,7 +560,7 @@ static int _netif_set_u16(kernel_pid_t dev, netopt_t opt, char *u16_str)
 
 static int _netif_set_i16(kernel_pid_t dev, netopt_t opt, char *i16_str)
 {
-    int16_t val = (int16_t)atoi(i16_str);
+    int16_t val = atoi(i16_str);
 
     if (gnrc_netapi_set(dev, opt, 0, (int16_t *)&val, sizeof(int16_t)) < 0) {
         printf("error: unable to set ");
@@ -578,7 +578,7 @@ static int _netif_set_i16(kernel_pid_t dev, netopt_t opt, char *i16_str)
 
 static int _netif_set_u8(kernel_pid_t dev, netopt_t opt, char *u8_str)
 {
-    uint8_t val = (uint8_t)atoi(u8_str);
+    uint8_t val = atoi(u8_str);
 
     if (gnrc_netapi_set(dev, opt, 0, (uint8_t *)&val, sizeof(uint8_t)) < 0) {
         printf("error: unable to set ");
@@ -1056,7 +1056,7 @@ int _netif_send(int argc, char **argv)
     }
 
     /* parse interface */
-    dev = (kernel_pid_t)atoi(argv[1]);
+    dev = atoi(argv[1]);
 
     if (!_is_iface(dev)) {
         puts("error: invalid interface given");
@@ -1114,7 +1114,7 @@ int _netif_config(int argc, char **argv)
         return 0;
     }
     else if (_is_number(argv[1])) {
-        kernel_pid_t dev = (kernel_pid_t)atoi(argv[1]);
+        kernel_pid_t dev = atoi(argv[1]);
 
         if (_is_iface(dev)) {
             if (argc < 3) {
diff --git a/sys/shell/commands/sc_saul_reg.c b/sys/shell/commands/sc_saul_reg.c
index 27d4b4ee7..7922292ec 100644
--- a/sys/shell/commands/sc_saul_reg.c
+++ b/sys/shell/commands/sc_saul_reg.c
@@ -116,7 +116,7 @@ static void write(int argc, char **argv)
     memset(&data, 0, sizeof(data));
     dim = ((argc - 3) > (int)PHYDAT_DIM) ? (int)PHYDAT_DIM : (argc - 3);
     for (int i = 0; i < dim; i++) {
-        data.val[i] = (int16_t)atoi(argv[i + 3]);
+        data.val[i] = atoi(argv[i + 3]);
     }
     /* print values before writing */
     printf("Writing to device #%i - %s\n", num, dev->name);
diff --git a/tests/driver_dynamixel/main.c b/tests/driver_dynamixel/main.c
index 521430ac9..061dea2a2 100644
--- a/tests/driver_dynamixel/main.c
+++ b/tests/driver_dynamixel/main.c
@@ -90,7 +90,7 @@ static void dir_disable_tx(uart_t uart) {
 
 static int parse_uart(char *arg)
 {
-    unsigned uart = (unsigned)atoi(arg);
+    unsigned uart = atoi(arg);
     if (uart >= UART_NUMOF) {
         printf("Error: Invalid UART_DEV device specified (%u).\n", uart);
         return -1;
@@ -104,7 +104,7 @@ static int parse_uart(char *arg)
 
 static int32_t parse_baud(char *arg)
 {
-    int32_t baud = (int32_t)atoi(arg);
+    int32_t baud = atoi(arg);
 
     for (size_t i = 0 ; i < ARRAY_LEN(baudrates) ; i++) {
         if (baud == baudrates[i]) {
@@ -118,7 +118,7 @@ static int32_t parse_baud(char *arg)
 
 static int parse_dev(char *arg)
 {
-    int dev = (int)atoi(arg);
+    int dev = atoi(arg);
     if (dev < 0 || 254 < dev) {
         printf("Error: Invalid device id (%s)\n", arg);
         return -1;
diff --git a/tests/driver_feetech/main.c b/tests/driver_feetech/main.c
index b2df7c945..c461d740f 100644
--- a/tests/driver_feetech/main.c
+++ b/tests/driver_feetech/main.c
@@ -81,7 +81,7 @@ static uart_half_duplex_t stream;
 
 static int parse_uart(char *arg)
 {
-    unsigned uart = (unsigned)atoi(arg);
+    unsigned uart = atoi(arg);
     if (uart >= UART_NUMOF) {
         printf("Error: Invalid UART_DEV device specified (%u).\n", uart);
         return -1;
@@ -95,7 +95,7 @@ static int parse_uart(char *arg)
 
 static int32_t parse_baud(char *arg)
 {
-    int32_t baud = (int32_t)atoi(arg);
+    int32_t baud = atoi(arg);
 
     for (size_t i = 0 ; i < ARRAY_LEN(baudrates) ; i++) {
         if (baud == baudrates[i]) {
@@ -109,7 +109,7 @@ static int32_t parse_baud(char *arg)
 
 static int parse_dev(char *arg)
 {
-    int dev = (int)atoi(arg);
+    int dev = atoi(arg);
     if (dev < 0 || 254 < dev) {
         printf("Error: Invalid device id (%s)\n", arg);
         return -1;
diff --git a/tests/driver_kw2xrf/main.c b/tests/driver_kw2xrf/main.c
index c9f74a3de..b2bb64701 100644
--- a/tests/driver_kw2xrf/main.c
+++ b/tests/driver_kw2xrf/main.c
@@ -62,7 +62,7 @@ static void _set_test_mode(int argc, char **argv, uint8_t mode)
 {
     (void) argc;
     if (_is_number(argv[1])) {
-        kernel_pid_t dev = (kernel_pid_t)atoi(argv[1]);
+        kernel_pid_t dev = atoi(argv[1]);
 
         if (_is_iface(dev)) {
             gnrc_netapi_set(dev, NETOPT_RF_TESTMODE, 0, (void *)&mode, sizeof(mode));
diff --git a/tests/driver_pcd8544/main.c b/tests/driver_pcd8544/main.c
index 58d6453f4..300b4f953 100644
--- a/tests/driver_pcd8544/main.c
+++ b/tests/driver_pcd8544/main.c
@@ -48,7 +48,7 @@ static int _contrast(int argc, char **argv)
         printf("usage: %s VAL [0-127]\n", argv[0]);
         return 1;
     }
-    val = (uint8_t)atoi(argv[1]);
+    val = atoi(argv[1]);
     pcd8544_set_contrast(&dev, val);
     return 0;
 }
@@ -61,7 +61,7 @@ static int _temp(int argc, char **argv)
         printf("usage: %s VAL [0-3]\n", argv[0]);
         return 1;
     }
-    val = (uint8_t)atoi(argv[1]);
+    val = atoi(argv[1]);
     pcd8544_set_tempcoef(&dev, val);
     return 0;
 }
@@ -74,7 +74,7 @@ static int _bias(int argc, char **argv)
         printf("usage: %s VAL [0-7]\n", argv[0]);
         return 1;
     }
-    val = (uint8_t)atoi(argv[1]);
+    val = atoi(argv[1]);
     pcd8544_set_bias(&dev, val);
     return 0;
 }
@@ -132,8 +132,8 @@ static int _write(int argc, char **argv)
         return -1;
     }
 
-    x = (uint8_t)atoi(argv[1]);
-    y = (uint8_t)atoi(argv[2]);
+    x = atoi(argv[1]);
+    y = atoi(argv[2]);
 
     pcd8544_write_s(&dev, x, y, argv[3]);
     return 0;
diff --git a/tests/driver_sdcard_spi/main.c b/tests/driver_sdcard_spi/main.c
index 24f5272b5..edab82a8b 100644
--- a/tests/driver_sdcard_spi/main.c
+++ b/tests/driver_sdcard_spi/main.c
@@ -189,8 +189,8 @@ static int _read(int argc, char **argv)
     bool print_as_char = false;
 
     if ((argc == 3) || (argc == 4)) {
-        blockaddr = (uint32_t)atoi(argv[1]);
-        cnt = (uint32_t)atoi(argv[2]);
+        blockaddr = atoi(argv[1]);
+        cnt = atoi(argv[2]);
         if (argc == 4 && (strcmp("-c", argv[3]) == 0)) {
             print_as_char = true;
         }
@@ -254,7 +254,7 @@ static int _write(int argc, char **argv)
     bool repeat_data = false;
 
     if (argc == 3 || argc == 4) {
-        bladdr = (int)atoi(argv[1]);
+        bladdr = atoi(argv[1]);
         data = argv[2];
         size = strlen(argv[2]);
         printf("will write '%s' (%d chars) at start of block %d\n", data, size, bladdr);
@@ -310,8 +310,8 @@ static int _copy(int argc, char **argv)
         return -1;
     }
 
-    src_block = (uint32_t)atoi(argv[1]);
-    dst_block = (uint32_t)atoi(argv[2]);
+    src_block = atoi(argv[1]);
+    dst_block = atoi(argv[2]);
 
     sd_rw_response_t rd_state;
     sdcard_spi_read_blocks(card, src_block, tmp_copy, SD_HC_BLOCK_SIZE, 1, &rd_state);
diff --git a/tests/driver_srf02/main.c b/tests/driver_srf02/main.c
index c3293ad65..028b55a14 100644
--- a/tests/driver_srf02/main.c
+++ b/tests/driver_srf02/main.c
@@ -56,7 +56,7 @@ static int cmd_init(int argc, char **argv)
         return 1;
     }
 
-    uint8_t addr = (uint8_t)atoi(argv[1]);
+    uint8_t addr = atoi(argv[1]);
 
     printf("Initializing SRF02 sensor at I2C_DEV(%i), address is %i\n... ",
            TEST_SRF02_I2C, (int)addr);
@@ -103,7 +103,7 @@ static int cmd_set_addr(int argc, char **argv)
         return 1;
     }
 
-    new_addr = (uint8_t)atoi(argv[1]);
+    new_addr = atoi(argv[1]);
     srf02_set_addr(&dev, new_addr);
     printf("Set address to %i\n", (int)new_addr);
     return 0;
diff --git a/tests/emb6/udp.c b/tests/emb6/udp.c
index f1ba76aa0..10930fcd9 100644
--- a/tests/emb6/udp.c
+++ b/tests/emb6/udp.c
@@ -126,10 +126,10 @@ int udp_cmd(int argc, char **argv)
             return 1;
         }
         if (argc > 5) {
-            num = (uint32_t)atoi(argv[5]);
+            num = atoi(argv[5]);
         }
         if (argc > 6) {
-            delay = (uint32_t)atoi(argv[6]);
+            delay = atoi(argv[6]);
         }
         return udp_send(argv[2], argv[3], argv[4], num, delay);
     }
diff --git a/tests/periph_uart/main.c b/tests/periph_uart/main.c
index 2f5269ce5..1657cf129 100644
--- a/tests/periph_uart/main.c
+++ b/tests/periph_uart/main.c
@@ -52,7 +52,7 @@ static char printer_stack[THREAD_STACKSIZE_MAIN];
 
 static int parse_dev(char *arg)
 {
-    unsigned dev = (unsigned)atoi(arg);
+    unsigned dev = atoi(arg);
     if (dev >= UART_NUMOF) {
         printf("Error: Invalid UART_DEV device specified (%u).\n", dev);
         return -1;
@@ -121,7 +121,7 @@ static int cmd_init(int argc, char **argv)
     if (dev < 0) {
         return 1;
     }
-    baud = (uint32_t)atoi(argv[2]);
+    baud = atoi(argv[2]);
 
     /* initialize UART */
     res = uart_init(UART_DEV(dev), baud, rx_cb, (void *)dev);