Index: src/as-system-info.c
--- src/as-system-info.c.orig
+++ src/as-system-info.c
@@ -45,7 +45,7 @@
 
 #if defined(__linux__)
 #include <sys/sysinfo.h>
-#elif defined(__FreeBSD__)
+#elif defined(__FreeBSD__) || defined(__OpenBSD__)
 #include <sys/types.h>
 #include <sys/sysctl.h>
 #endif
@@ -408,6 +408,10 @@ as_get_physical_memory_total (void)
 #elif defined(__FreeBSD__)
 	unsigned long physmem;
 	sysctl ((int[]){ CTL_HW, HW_PHYSMEM }, 2, &physmem, &(size_t){ sizeof (physmem) }, NULL, 0);
+	return physmem / MB_IN_BYTES;
+#elif defined(__OpenBSD__)
+	unsigned long physmem;
+	sysctl ((int[]){ CTL_HW, HW_PHYSMEM64 }, 2, &physmem, &(size_t){ sizeof (physmem) }, NULL, 0);
 	return physmem / MB_IN_BYTES;
 #else
 #error "Implementation of as_get_physical_memory_total() missing for this OS."