diff --git a/pigpio.c b/pigpio.c
index 1126ec3..56c3489 100644
--- a/pigpio.c
+++ b/pigpio.c
@@ -970,6 +970,7 @@ typedef struct
    int timeout;
    unsigned ex;
    void *userdata;
+   int fd;
    int inited;
 } gpioISR_t;
 
@@ -11477,12 +11478,16 @@ static void *pthISRThread(void *x)
 
    sprintf(buf, "/sys/class/gpio/gpio%d/value", isr->gpio);
 
+   isr->fd = -1; /* no fd assigned */
+
    if ((fd = open(buf, O_RDONLY)) < 0)
    {
       DBG(DBG_ALWAYS, "gpio %d not exported", isr->gpio);
       return NULL;
    }
 
+   isr->fd = fd; /* store fd so it can be closed */
+
    pfd.fd = fd;
 
    pfd.events = POLLPRI;
@@ -11602,6 +11607,13 @@ static int intGpioSetISRFunc(
       if (gpioISR[gpio].pth) /* delete any existing ISR */
       {
          gpioStopThread(gpioISR[gpio].pth);
+
+         if (gpioISR[gpio].fd >= 0)
+         {
+            close(gpioISR[gpio].fd);
+            gpioISR[gpio].fd = -1;
+         }
+
          gpioISR[gpio].func = NULL;
          gpioISR[gpio].pth = NULL;
       }
diff --git a/pigpio.h b/pigpio.h
index 03ebdca..046af93 100644
--- a/pigpio.h
+++ b/pigpio.h
@@ -31,7 +31,7 @@ For more information, please refer to <http://unlicense.org/>
 #include <stdint.h>
 #include <pthread.h>
 
-#define PIGPIO_VERSION 6904
+#define PIGPIO_VERSION 6905
 
 /*TEXT