diff --git a/configure.ac b/configure.ac
index 8f7fff3..3bb6184 100644
--- a/configure.ac
+++ b/configure.ac
@@ -18,7 +18,15 @@ AC_PROG_RANLIB
 
 dnl Checks for header files.
 AC_HEADER_STDC
-AC_CHECK_HEADERS(syslog.h)
+AC_CHECK_HEADERS([sys/param.h syslog.h])
+# sys/sysctl.h requires sys/types.h on FreeBSD
+# sys/sysctl.h requires sys/param.h on OpenBSD
+AC_CHECK_HEADERS([sys/sysctl.h], [], [],
+[#include <sys/types.h>
+#if HAVE_SYS_PARAM_H
+#include <sys/param.h>
+#endif
+])
 
 AC_FUNC_ALLOCA
 
diff --git a/cpu-miner.c b/cpu-miner.c
index 8652851..c9ba6c9 100644
--- a/cpu-miner.c
+++ b/cpu-miner.c
@@ -18,14 +18,18 @@
 #include <unistd.h>
 #include <sys/time.h>
 #include <time.h>
-#if defined(WIN32)
+#ifdef WIN32
 #include <windows.h>
-#elif defined(sun) || defined(__sun)
-#include <sys/resource.h>
 #else
 #include <sys/resource.h>
+#if HAVE_SYS_SYSCTL_H
+#include <sys/types.h>
+#if HAVE_SYS_PARAM_H
+#include <sys/param.h>
+#endif
 #include <sys/sysctl.h>
 #endif
+#endif
 #include <getopt.h>
 #include <jansson.h>
 #include <curl/curl.h>