diff --git a/configure.ac b/configure.ac
index 24b8850d1..9afa9d98b 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1304,6 +1304,8 @@ fi
 
 # Use AC_CHECK_HEADERS so the HAVE_*_H symbol gets defined
 AC_CHECK_HEADERS([ncurses/termcap.h termcap.h])
+AC_CHECK_HEADERS([sys/sysctl.h])
+
 
 # --enable-openmp: Use OpenMP on multi-core processors
 AC_ARG_ENABLE([openmp],
diff --git a/src/frontend/get_avail_mem_size.c b/src/frontend/get_avail_mem_size.c
index 3d468b659..ebec4fd89 100644
--- a/src/frontend/get_avail_mem_size.c
+++ b/src/frontend/get_avail_mem_size.c
@@ -15,7 +15,7 @@
 #include <unistd.h>
 #include <sys/types.h>
 #include <sys/param.h>
-#if defined(BSD)
+#if defined(BSD) && defined(HAVE_SYS_SYSCTL_H)
 #include <sys/sysctl.h>
 #endif
 #if defined(__APPLE__) && defined(__MACH__)
@@ -91,7 +91,7 @@ unsigned long long getAvailableMemorySize(void)
     /* Linux/UNIX variants. ------------------------------------------- */
     /* Prefer sysctl() over sysconf() except sysctl() HW_REALMEM and HW_PHYSMEM */
 
-#if defined(CTL_HW) && (defined(HW_MEMSIZE) || defined(HW_PHYSMEM64))
+#if defined(CTL_HW) && (defined(HW_MEMSIZE) || defined(HW_PHYSMEM64)) && defined(HAVE_SYS_SYSCTL_H)
     int mib[2];
     mib[0] = CTL_HW;
 #if defined(HW_MEMSIZE)
@@ -119,7 +119,7 @@ unsigned long long getAvailableMemorySize(void)
     return (size_t)sysconf( _SC_PHYS_PAGES ) *
         (size_t)sysconf( _SC_PAGE_SIZE );
 
-#elif defined(CTL_HW) && (defined(HW_PHYSMEM) || defined(HW_REALMEM))
+#elif defined(CTL_HW) && (defined(HW_PHYSMEM) || defined(HW_REALMEM)) && defined(HAVE_SYS_SYSCTL_H)
     /* DragonFly BSD, FreeBSD, NetBSD, OpenBSD, and OSX. -------- */
     int mib[2];
     mib[0] = CTL_HW;
diff --git a/src/frontend/get_phys_mem_size.c b/src/frontend/get_phys_mem_size.c
index 3ebb92407..c40e5a327 100644
--- a/src/frontend/get_phys_mem_size.c
+++ b/src/frontend/get_phys_mem_size.c
@@ -17,7 +17,7 @@
 #include <unistd.h>
 #include <sys/types.h>
 #include <sys/param.h>
-#if defined(BSD)
+#if defined(BSD) && defined(HAVE_SYS_SYSCTL_H)
 #include <sys/sysctl.h>
 #endif
 
@@ -98,7 +98,7 @@ unsigned long long getMemorySize(void)
     return (unsigned long long) sysconf(_SC_PHYS_PAGES) *
             (unsigned long long) sysconf(_SC_PAGE_SIZE);
 
-#elif defined(CTL_HW) && (defined(HW_PHYSMEM) || defined(HW_REALMEM))
+#elif defined(CTL_HW) && (defined(HW_PHYSMEM) || defined(HW_REALMEM)) && defined(HAVE_SYS_SYSCTL_H)
     /* DragonFly BSD, FreeBSD, NetBSD, OpenBSD, and OSX. -------- */
     int mib[2];
     mib[0] = CTL_HW;