diff --git a/sys/include/net/csma_sender.h b/sys/include/net/csma_sender.h
index 00d2278307..579a711d9f 100644
--- a/sys/include/net/csma_sender.h
+++ b/sys/include/net/csma_sender.h
@@ -81,6 +81,8 @@ void csma_sender_set_max_backoffs(uint8_t val);
 /**
  * @brief   Sends a 802.15.4 frame using the CSMA/CA method
  *
+ * @pre `dev != NULL`
+ *
  * If the transceiver can (and is configured to) do hardware-assisted
  * CSMA/CA, this feature is used. Otherwise, a software procedure is used.
  *
@@ -103,6 +105,8 @@ int csma_sender_csma_ca_send(netdev2_t *dev, struct iovec *vector,
 /**
  * @brief   Sends a 802.15.4 frame when medium is avaiable.
  *
+ * @pre `dev != NULL`
+ *
  * This function is useful for sending packets without the whole CSMA/CA
  * procedure, but *after* ensuring medium is available, that is after a
  * successful CCA.
diff --git a/sys/net/link_layer/csma_sender/csma_sender.c b/sys/net/link_layer/csma_sender/csma_sender.c
index ca88023c6d..2bdedd1e16 100644
--- a/sys/net/link_layer/csma_sender/csma_sender.c
+++ b/sys/net/link_layer/csma_sender/csma_sender.c
@@ -16,6 +16,7 @@
  * @}
  */
 
+#include <assert.h>
 #include <errno.h>
 #include <stdbool.h>
 
@@ -138,6 +139,7 @@ int csma_sender_csma_ca_send(netdev2_t *dev, struct iovec *vector,
 {
     netopt_enable_t hwfeat;
 
+    assert(dev);
     /* Does the transceiver do automatic CSMA/CA when sending? */
     int res = dev->driver->get(dev,
                                NETOPT_CSMA,
@@ -210,6 +212,7 @@ int csma_sender_cca_send(netdev2_t *dev, struct iovec *vector, unsigned count)
 {
     netopt_enable_t hwfeat;
 
+    assert(dev);
     /* Does the transceiver do automatic CCA before sending? */
     int res = dev->driver->get(dev,
                                NETOPT_AUTOCCA,