diff --git a/driver_library/src/ethosu.cpp b/driver_library/src/ethosu.cpp
index 64aee4d..dcdde8c 100644
--- a/driver_library/src/ethosu.cpp
+++ b/driver_library/src/ethosu.cpp
@@ -20,7 +20,9 @@
 #include <uapi/ethosu.h>
 
 #include <algorithm>
+#include <cerrno>
 #include <cstdlib>
+#include <cstring>
 #include <exception>
 #include <fstream>
 #include <iomanip>
@@ -104,7 +106,7 @@
 __attribute__((weak)) int eioctl(int fd, unsigned long cmd, void *data = nullptr) {
     int ret = ::ioctl(fd, cmd, data);
     if (ret < 0) {
-        throw EthosU::Exception("IOCTL failed");
+        throw EthosU::Exception(string("IOCTL cmd=").append(to_string(cmd) + " failed: " + strerror(errno)).c_str());
     }
 
     Log(Severity::Debug) << "ioctl. fd=" << fd << ", cmd=" << setw(8) << setfill('0') << hex << cmd << ", ret=" << ret