diff --git a/efunc.h b/efunc.h
index 3a76de5..661c473 100644
--- a/efunc.h
+++ b/efunc.h
@@ -65,10 +65,14 @@
 /* eval.c */
 #include "eval.h"
 
+#if	BSD | SVR4
 /* lock.c */
 #include "lock.h"
 
+#if (FILOCK && BSD) || SVR4
 /* pklock.c */
 #include "pklock.h"
+#endif
+#endif
 
 #endif
diff --git a/lock.h b/lock.h
index b1f9d75..1183a10 100644
--- a/lock.h
+++ b/lock.h
@@ -1,6 +1,14 @@
+#ifndef _LOCK_H_
+#define _LOCK_H_
+
+#if	BSD | SVR4
+
 int lockchk( char *fname) ;
 int lockrel( void) ;
 int lock( char *fname) ;
 int unlock( char *fname) ;
 void lckerror( char *errstr) ;
 
+#endif
+
+#endif
diff --git a/pklock.h b/pklock.h
index fd91c1c..a75ac02 100644
--- a/pklock.h
+++ b/pklock.h
@@ -1,3 +1,11 @@
+#ifndef _PKLOCK_H_
+#define _PKLOCK_H_
+
+#if (FILOCK && BSD) || SVR4
+
 char *dolock( char *fname) ;
 char *undolock( char *fname) ;
 
+#endif
+
+#endif