diff --git a/configure.ac b/configure.ac
index c16adec..10fe412 100644
--- a/configure.ac
+++ b/configure.ac
@@ -103,7 +103,7 @@ AC_FUNC_REALLOC
 AC_CHECK_FUNCS([alarm dup2 gettimeofday localtime_r memset socket strcasecmp \
 		strchr strcspn strerror strncasecmp strpbrk strrchr strtol \
 		getifaddrs if_nameindex sigaction nanosleep \
-		gettimeofday getrusage setitimer tcsetattr])
+		gettimeofday getrusage setitimer tcsetattr mlockall])
 
 # Check for CPU.
 # This requires install-sh, config.sub, config.guess from automake.
diff --git a/src/dpimp.c b/src/dpimp.c
index 3516cf5..10c6a07 100644
--- a/src/dpimp.c
+++ b/src/dpimp.c
@@ -608,7 +608,7 @@ main(int argc, char **argv)
 	/* And ensure its memory is locked too, since the lockage isn't
 	** inherited over a fork().  Don't bother warning if it fails.
 	*/
-#if CENV_SYS_DECOSF || CENV_SYS_SOLARIS || CENV_SYS_LINUX
+#if HAVE_MLOCKALL
 	(void) mlockall(MCL_CURRENT|MCL_FUTURE);
 #endif
 	progname = progname_r;	/* Reset progname to indicate identity */
diff --git a/src/dpni20.c b/src/dpni20.c
index 78ce268..149fc2f 100644
--- a/src/dpni20.c
+++ b/src/dpni20.c
@@ -432,7 +432,7 @@ main(int argc, char **argv)
 	/* And ensure its memory is locked too, since the lockage isn't
 	** inherited over a fork().  Don't bother warning if it fails.
 	*/
-#if CENV_SYS_DECOSF || CENV_SYS_SOLARIS || CENV_SYS_LINUX
+#if HAVE_MLOCKALL
 	(void) mlockall(MCL_CURRENT|MCL_FUTURE);
 #endif
 	progname = progname_r;	/* Reset progname to indicate identity */
diff --git a/src/dpsup.c b/src/dpsup.c
index 75807d8..5284467 100644
--- a/src/dpsup.c
+++ b/src/dpsup.c
@@ -488,7 +488,7 @@ int dp_main(register struct dp_s *dp, int argc, char **argv)
 	** beforehand - only warn if an error isn't EPERM and hence is
 	** unusual.
 	*/
-#if CENV_SYS_DECOSF || CENV_SYS_SOLARIS || CENV_SYS_LINUX
+#if HAVE_MLOCKALL
 	if (mlockall(MCL_CURRENT|MCL_FUTURE) != 0) {
 	    if (errno != EPERM)
 		fprintf(stderr, "[%s: mlockall failed - %s]\r\n",
diff --git a/src/osdsup.c b/src/osdsup.c
index 495859d..fa73788 100644
--- a/src/osdsup.c
+++ b/src/osdsup.c
@@ -1666,14 +1666,14 @@ os_mmkill(osmm_t mm, char *ptr)
 
 /* Attempt to lock all of our process memory now and in the future.
 */
-#if CENV_SYS_DECOSF || CENV_SYS_SOLARIS
+#if HAVE_MLOCKALL
 # include <sys/mman.h>
 #endif
 
 int
 os_memlock(int dolock)
 {
-#if CENV_SYS_DECOSF || CENV_SYS_SOLARIS
+#if HAVE_MLOCKALL
     /* Both Solaris and OSF/1 have mlockall() which looks like what we want.
     ** It requires being the super-user, but don't bother to check here,
     ** just return error if it fails for any reason.