diff --git a/ChangeLog b/ChangeLog
index 4b1a387..5bd8b25 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -22,6 +22,7 @@ Version NEXT
 	  exit build if function is unavailable.
 	parsecheck: report if all tests passed / some failed
 	parsecheck: init all fields in testcase results
+	SConstruct: declare CPP constant SIZEOF_LONG
 
 Version 2.8.1b29 - 24 Aug 2019
 	added scons command line argument without-fspscan=yes for building
diff --git a/SConstruct b/SConstruct
index 5796f27..38dafd2 100644
--- a/SConstruct
+++ b/SConstruct
@@ -145,6 +145,8 @@ if not conf.CheckType("union semun", "#include <sys/types.h>\n#include <sys/ipc.
        conf.env.Append(CPPFLAGS = "-D_SEM_SEMUN_UNDEFINED=1")
 conf.checkForLargeFiles(conf)
 if not conf.CheckFunc('fseeko'): Exit(1)
+ulong=conf.CheckTypeSize('long')
+conf.env.Append(CPPFLAGS = '-DSIZEOF_LONG='+str(ulong))
 conf.checkForLockingType(conf)
 if conf.checkReliableSignals():
     conf.env.Append(CPPFLAGS = '-DRELIABLE_SIGNALS')