Index: /issm/trunk-jpl/m4/issm_options.m4
===================================================================
--- /issm/trunk-jpl/m4/issm_options.m4	(revision 25647)
+++ /issm/trunk-jpl/m4/issm_options.m4	(revision 25648)
@@ -205,4 +205,7 @@
 	AC_MSG_RESULT([${IS_MAC}])
 
+	dnl If macOS, check if system copy of libc has fmemopen (if it is not 
+	dnl macOS, we do not check, but still must set SYSTEM_HAS_FMEMOPEN)
+	SYSTEM_FMEMOPEN="no"
 	if test "${IS_MAC}" == "yes"; then
 		AC_MSG_CHECKING([if system libc has fmemopen])
@@ -211,10 +214,9 @@
 			AC_DEFINE([_SYSTEM_FMEMOPEN_], [1], [does system libc have fmemopen])
 		else
-			SYSTEM_FMEMOPEN="no"
 			AC_DEFINE([_SYSTEM_FMEMOPEN_], [0], [does system libc have fmemopen])
 		fi
-		AM_CONDITIONAL([SYSTEM_HAS_FMEMOPEN], [test "${SYSTEM_FMEMOPEN}" == "yes"])
-		AC_MSG_RESULT([${SYSTEM_FMEMOPEN}])
-	fi
+	fi
+	AM_CONDITIONAL([SYSTEM_HAS_FMEMOPEN], [test "${SYSTEM_FMEMOPEN}" == "yes"])
+	AC_MSG_RESULT([${SYSTEM_FMEMOPEN}])
 
 	IS_WINDOWS=no