diff --git a/CMakeLists.txt b/CMakeLists.txt
index fe9b596..f82ee96 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -146,6 +146,7 @@
 check_symbol_exists(fork unistd.h HAVE_FORK)
 check_symbol_exists(execve unistd.h HAVE_EXECVE)
 check_symbol_exists(ftruncate unistd.h HAVE_FTRUNCATE)
+check_symbol_exists(nice unistd.h HAVE_NICE)
 check_symbol_exists(setgid unistd.h HAVE_SETGID)
 check_symbol_exists(setuid unistd.h HAVE_SETUID)
 check_symbol_exists(setsid unistd.h HAVE_SETSID)
diff --git a/config.h.cmake.in b/config.h.cmake.in
index 25273ac..c1f5848 100644
--- a/config.h.cmake.in
+++ b/config.h.cmake.in
@@ -209,7 +209,7 @@
 #cmakedefine HAVE_NET_TUN_IF_TUN_H
 
 /* Define to 1 if you have the `nice' function. */
-#undef HAVE_NICE
+#cmakedefine HAVE_NICE
 
 /* Define to 1 if you have the `openlog' function. */
 #cmakedefine HAVE_OPENLOG