diff --git a/src/core/sys/freebsd/config.d b/src/core/sys/freebsd/config.d
new file mode 100644
index 00000000000..1a61f901ca4
--- /dev/null
+++ b/src/core/sys/freebsd/config.d
@@ -0,0 +1,22 @@
+/**
+ * D header file for FreeBSD
+ *
+ * Authors: Iain Buclaw
+ */
+module core.sys.freebsd.config;
+
+version (FreeBSD):
+
+public import core.sys.posix.config;
+
+// __FreeBSD_version numbers are documented in the Porter's Handbook.
+// https://svnweb.freebsd.org/base/head/sys/sys/param.h?view=markup
+     version (FreeBSD_12) enum __FreeBSD_version = 1202000;
+else version (FreeBSD_11) enum __FreeBSD_version = 1104000;
+else version (FreeBSD_10) enum __FreeBSD_version = 1004000;
+else version (FreeBSD_9)  enum __FreeBSD_version = 903000;
+else version (FreeBSD_8)  enum __FreeBSD_version = 804000;
+else static assert(false "Unsupported version of FreeBSD");
+
+// First version of FreeBSD to support 64-bit stat buffer.
+enum INO64_FIRST = 1200031;
diff --git a/src/core/sys/freebsd/sys/event.d b/src/core/sys/freebsd/sys/event.d
index c8bc141be6b..bb402d197cc 100644
--- a/src/core/sys/freebsd/sys/event.d
+++ b/src/core/sys/freebsd/sys/event.d
@@ -18,6 +18,7 @@ extern (C):
 nothrow:
 @nogc:
 
+import core.sys.freebsd.config;
 import core.stdc.stdint;    // intptr_t, uintptr_t
 import core.sys.posix.time; // timespec
 
@@ -43,7 +44,7 @@ extern(D) void EV_SET(kevent_t* kevp, typeof(kevent_t.tupleof) args)
     *kevp = kevent_t(args);
 }
 
-version (FreeBSD_12)
+static if (__FreeBSD_version >= 1200000 && __FreeBSD_version < 1300000)
 {
     struct kevent_t
     {
@@ -56,7 +57,7 @@ version (FreeBSD_12)
         ulong[4]  ext;
     }
 }
-else version (FreeBSD_11)
+else static if (__FreeBSD_version < 1200000)
 {
     struct kevent_t
     {
diff --git a/src/core/sys/freebsd/sys/mount.d b/src/core/sys/freebsd/sys/mount.d
index cca60159afc..42725750acc 100644
--- a/src/core/sys/freebsd/sys/mount.d
+++ b/src/core/sys/freebsd/sys/mount.d
@@ -11,6 +11,7 @@ module core.sys.freebsd.sys.mount;
 
 version (FreeBSD):
 
+import core.sys.freebsd.config;
 import core.stdc.config : c_long;
 import core.sys.posix.sys.stat : stat_t;
 import core.sys.posix.sys.types : uid_t;
@@ -33,12 +34,12 @@ struct fid
 
 enum MFSNAMELEN = 16;
 
-version (FreeBSD_12)
+static if (__FreeBSD_version >= 1200000 && __FreeBSD_version < 1300000)
 {
     enum MNAMELEN   = 1024;
     enum STATFS_VERSION = 0x20140518;
 }
-else version (FreeBSD_11)
+else static if (__FreeBSD_version < 1200000)
 {
     enum MNAMELEN   = 88;
     enum STATFS_VERSION = 0x20030518;
diff --git a/src/core/sys/posix/dirent.d b/src/core/sys/posix/dirent.d
index a07046b9ba3..1133162e7f1 100644
--- a/src/core/sys/posix/dirent.d
+++ b/src/core/sys/posix/dirent.d
@@ -141,6 +141,8 @@ else version (Darwin)
 }
 else version (FreeBSD)
 {
+    import core.sys.freebsd.config;
+
     // https://github.com/freebsd/freebsd/blob/master/sys/sys/dirent.h
     enum
     {
@@ -155,7 +157,7 @@ else version (FreeBSD)
         DT_WHT      = 14
     }
 
-    version (FreeBSD_12)
+    static if (__FreeBSD_version >= 1200000 && __FreeBSD_version < 1300000)
     {
         struct dirent
         {
@@ -168,7 +170,7 @@ else version (FreeBSD)
             char[256] d_name = 0;
         }
     }
-    else version (FreeBSD_11)
+    else static if (__FreeBSD_version < 1200000)
     {
         align(4)
         struct dirent
diff --git a/src/core/sys/posix/sys/stat.d b/src/core/sys/posix/sys/stat.d
index ddc8aefef66..31ba2ead1f2 100644
--- a/src/core/sys/posix/sys/stat.d
+++ b/src/core/sys/posix/sys/stat.d
@@ -1078,9 +1078,10 @@ else version (Darwin)
 }
 else version (FreeBSD)
 {
-    // https://github.com/freebsd/freebsd/blob/master/sys/sys/stat.h
+    import core.sys.freebsd.config;
 
-    version (FreeBSD_12)
+    // https://github.com/freebsd/freebsd/blob/master/sys/sys/stat.h
+    static if (__FreeBSD_version >= INO64_FIRST)
     {
         struct stat_t
         {
@@ -1122,7 +1123,7 @@ else version (FreeBSD)
             ulong[10] st_spare;
         }
     }
-    else version (FreeBSD_11)
+    else
     {
         struct stat_t
         {
@@ -1154,8 +1155,6 @@ else version (FreeBSD)
             ubyte[16 - timespec.sizeof] padding;
         }
     }
-    else
-        static assert(0, "Unsupported version of FreeBSD");
 
     enum S_IRUSR    = 0x100; // octal 0000400
     enum S_IWUSR    = 0x080; // octal 0000200
diff --git a/src/core/sys/posix/sys/types.d b/src/core/sys/posix/sys/types.d
index 1c5054ea3c7..ce280386663 100644
--- a/src/core/sys/posix/sys/types.d
+++ b/src/core/sys/posix/sys/types.d
@@ -169,17 +169,19 @@ else version (Darwin)
 }
 else version (FreeBSD)
 {
+    import core.sys.freebsd.config;
+
     // https://github.com/freebsd/freebsd/blob/master/sys/sys/_types.h
     alias long      blkcnt_t;
 
-    version (FreeBSD_12)
+    static if (__FreeBSD_version >= 1200000 && __FreeBSD_version < 1300000)
     {
         alias ulong blksize_t;
         alias ulong dev_t;
         alias ulong ino_t;
         alias ulong nlink_t;
     }
-    else version (FreeBSD_11)
+    else static if (__FreeBSD_version < 1200000)
     {
         alias uint   blksize_t;
         alias uint   dev_t;