Compile error 4.3.9

make[1]: Entering directory `/tmp/xymon-4.3.9/xymonnet'
gcc -g -O2 -Wall -Wno-unused -Wno-pointer-sign -D_REENTRANT
-D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64 -DLINUX -I.
-I/tmp/xymon-4.3.9/include    -c -o httptest.o httptest.c
httptest.c: In function âadd_http_testâ:
httptest.c:552:84: error: âerrnoâ undeclared (first use in this function)
httptest.c:552:84: note: each undeclared identifier is reported only once
for each function it appears in
make[1]: *** [httptest.o] Error 1
make[1]: Leaving directory `/tmp/xymon-4.3.9/xymonnet'
make: *** [xymonnet-build] Error 2