diff --git a/net/rpdutils/src/daemon.cxx b/net/rpdutils/src/daemon.cxx
index 54d00140817e57c16ae6c203c77e7574a24cf58c..8411800668d310b6a6038eb8a5a6aa7a27c00916 100644
--- a/net/rpdutils/src/daemon.cxx
+++ b/net/rpdutils/src/daemon.cxx
@@ -28,6 +28,10 @@
 #  include <fcntl.h>
 #endif
 
+#ifdef __linux__
+#define linux
+#endif
+
 #ifdef SIGTSTP
 #include <sys/file.h>
 #include <sys/ioctl.h>
diff --git a/net/rpdutils/src/rpdutils.cxx b/net/rpdutils/src/rpdutils.cxx
index b16a5b860bc434176390aa7b86929cd2304f5a46..946d6ed9fa4f708da3c174e03cbf87438bd1d24b 100644
--- a/net/rpdutils/src/rpdutils.cxx
+++ b/net/rpdutils/src/rpdutils.cxx
@@ -42,6 +42,10 @@
 #   define cygwingcc
 #endif
 
+#ifdef __linux__
+#define linux
+#endif
+
 #if defined(linux) || defined(__sun) || defined(__sgi) || \
     defined(_AIX) || defined(__FreeBSD__) || defined(__OpenBSD__) || \
     defined(__APPLE__) || defined(__MACH__) || defined(cygwingcc)
diff --git a/proof/proofd/src/proofd.cxx b/proof/proofd/src/proofd.cxx
index a2c014259e033e0b5f4c51c8c9bd3923b5b9f5e3..f4ed377cc8a50bbbdb913aafd2b88ff640e56f46 100644
--- a/proof/proofd/src/proofd.cxx
+++ b/proof/proofd/src/proofd.cxx
@@ -181,6 +181,9 @@
 #if defined(__CYGWIN__) && defined(__GNUC__)
 #   define cygwingcc
 #endif
+#ifdef __linux__
+#define linux
+#endif
 #if defined(linux) || defined(__sun) || defined(__sgi) || \
     defined(_AIX) || defined(__FreeBSD__) || defined(__APPLE__) || \
     defined(__MACH__) || defined(cygwingcc) || defined(__OpenBSD__)