diff --git a/pigpio.c b/pigpio.c
index ff1fb5d..a9c9190 100644
--- a/pigpio.c
+++ b/pigpio.c
@@ -1240,6 +1240,9 @@ static uint32_t sockNetAddr[MAX_CONNECT_ADDRESSES];
 
 static int numSockNetAddr = 0;
 
+// sif_mutex is used to run socket interface single threaded
+static pthread_mutex_t sif_mutex = PTHREAD_MUTEX_INITIALIZER;
+
 static uint32_t reportedLevel = 0;
 
 static int waveClockInited = 0;
@@ -1868,6 +1871,8 @@ static int myDoCommand(uintptr_t *p, unsigned bufSize, char *buf)
    int masked;
    res = 0;
 
+   pthread_mutex_lock(&sif_mutex);
+
    switch (p[0])
    {
       case PI_CMD_BC1:
@@ -2514,6 +2519,7 @@ static int myDoCommand(uintptr_t *p, unsigned bufSize, char *buf)
          break;
    }
 
+   pthread_mutex_unlock(&sif_mutex);
    return res;
 }