Can't compile source

In file included from /home/pi/src/MaxScale/query_classifier/qc_mysqlembedded/qc_mysqlembedded.cc:60:0:
/home/pi/src/MaxScale/query_classifier/qc_mysqlembedded/qc_mysqlembedded.cc: In function ‘bool parse_query(GWBUF*)’:
/home/pi/src/MaxScale/server/include/log_manager.h:116:82: error: format ‘%lu’ expects argument of type ‘long unsigned int’, but argument 6 has type ‘size_t

’ [-Werror=format=]
mxs_log_message(priority, _FILE, __LINE, __func, format, ##VA_ARGS_)
^
/home/pi/src/MaxScale/server/include/log_manager.h:124:34: note: in expansion of macro ‘MXS_LOG_MESSAGE’
#define MXS_ERROR(format, ...) MXS_LOG_MESSAGE(LOG_ERR, format, ##_VA_ARGS_)
^
/home/pi/src/MaxScale/query_classifier/qc_mysqlembedded/qc_mysqlembedded.cc:220:9: note: in expansion of macro ‘MXS_ERROR’
MXS_ERROR("Length (%lu) is 0 or query string allocation failed (%p). Buffer is %lu bytes.",
^
/home/pi/src/MaxScale/server/include/log_manager.h:116:82: error: format ‘%lu’ expects argument of type ‘long unsigned int’, but argument 8 has type ‘int’ [-Werror=format=]
mxs_log_message(priority, _FILE, __LINE, __func, format, ##VA_ARGS_)
^
/home/pi/src/MaxScale/server/include/log_manager.h:124:34: note: in expansion of macro ‘MXS_LOG_MESSAGE’
#define MXS_ERROR(format, ...) MXS_LOG_MESSAGE(LOG_ERR, format, ##_VA_ARGS_)
^
/home/pi/src/MaxScale/query_classifier/qc_mysqlembedded/qc_mysqlembedded.cc:220:9: note: in expansion of macro ‘MXS_ERROR’
MXS_ERROR("Length (%lu) is 0 or query string allocation failed (%p). Buffer is %lu bytes.",
^
cc1plus: all warnings being treated as errors
query_classifier/qc_mysqlembedded/CMakeFiles/qc_mysqlembedded.dir/build.make:54: recipe for target 'query_classifier/qc_mysqlembedded/CMakeFiles/qc_mysqlembedded.dir/qc_mysqlembedded.cc.o' failed
make[2]: *** [query_classifier/qc_mysqlembedded/CMakeFiles/qc_mysqlembedded.dir/qc_mysqlembedded.cc.o] Error 1
CMakeFiles/Makefile2:392: recipe for target 'query_classifier/qc_mysqlembedded/CMakeFiles/qc_mysqlembedded.dir/all' failed
make[1]: *** [query_classifier/qc_mysqlembedded/CMakeFiles/qc_mysqlembedded.dir/all] Error 2
Makefile:127: recipe for target 'all' failed
make: *** [all] Error 2