diff --git a/include/coap3/coap_mutex_internal.h b/include/coap3/coap_mutex_internal.h
index aeb127ac..1b08e35f 100644
--- a/include/coap3/coap_mutex_internal.h
+++ b/include/coap3/coap_mutex_internal.h
@@ -29,8 +29,8 @@
 #include <pthread.h>
 
 typedef pthread_mutex_t coap_mutex_t;
-#define COAP_MUTEX_DEFINE(_name)			\
-	static coap_mutex_t _name = PTHREAD_MUTEX_INITIALIZER
+#define COAP_MUTEX_DEFINE(_name)                        \
+        static coap_mutex_t _name = PTHREAD_MUTEX_INITIALIZER
 #define coap_mutex_lock(a) pthread_mutex_lock(a)
 #define coap_mutex_trylock(a) pthread_mutex_trylock(a)
 #define coap_mutex_unlock(a) pthread_mutex_unlock(a)
@@ -40,8 +40,8 @@ typedef pthread_mutex_t coap_mutex_t;
 #include <mutex.h>
 
 typedef mutex_t coap_mutex_t;
-#define COAP_MUTEX_DEFINE(_name)			\
-	static coap_mutex_t _name = MUTEX_INIT
+#define COAP_MUTEX_DEFINE(_name)                        \
+        static coap_mutex_t _name = MUTEX_INIT
 #define coap_mutex_lock(a) mutex_lock(a)
 #define coap_mutex_trylock(a) mutex_trylock(a)
 #define coap_mutex_unlock(a) mutex_unlock(a)
@@ -52,8 +52,8 @@ typedef mutex_t coap_mutex_t;
 #if NO_SYS
 /* Single threaded, no-op'd in lwip/sys.h */
 typedef int coap_mutex_t;
-#define COAP_MUTEX_DEFINE(_name)			\
-	static coap_mutex_t _name
+#define COAP_MUTEX_DEFINE(_name)                        \
+        static coap_mutex_t _name
 #define coap_mutex_lock(a) *(a) = 1
 #define coap_mutex_trylock(a) *(a) = 1
 #define coap_mutex_unlock(a) *(a) = 0
@@ -64,8 +64,8 @@ typedef int coap_mutex_t;
 #elif defined(WITH_CONTIKI)
 /* Contiki does not have a mutex API, used as single thread */
 typedef int coap_mutex_t;
-#define COAP_MUTEX_DEFINE(_name)			\
-	static coap_mutex_t _name
+#define COAP_MUTEX_DEFINE(_name)                        \
+        static coap_mutex_t _name
 #define coap_mutex_lock(a) *(a) = 1
 #define coap_mutex_trylock(a) *(a) = 1
 #define coap_mutex_unlock(a) *(a) = 0
@@ -74,8 +74,8 @@ typedef int coap_mutex_t;
 #include <zephyr/sys/mutex.h>
 
 typedef struct k_mutex coap_mutex_t;
-#define COAP_MUTEX_DEFINE(_name)			\
-	static SYS_MUTEX_DEFINE(_name)
+#define COAP_MUTEX_DEFINE(_name)                        \
+        static SYS_MUTEX_DEFINE(_name)
 #define coap_mutex_lock(a) sys_mutex_lock(a, K_FOREVER)
 #define coap_mutex_trylock(a) sys_mutex_lock(a, K_NO_WAIT)
 #define coap_mutex_unlock(a) sys_mutex_unlock(a)
@@ -84,8 +84,8 @@ typedef struct k_mutex coap_mutex_t;
 /* define stub mutex functions */
 #warning "stub mutex functions"
 typedef int coap_mutex_t;
-#define COAP_MUTEX_DEFINE(_name)			\
-	static coap_mutex_t _name
+#define COAP_MUTEX_DEFINE(_name)                        \
+        static coap_mutex_t _name
 #define coap_mutex_lock(a) *(a) = 1
 #define coap_mutex_trylock(a) *(a) = 1
 #define coap_mutex_unlock(a) *(a) = 0