diff --git a/Makefile b/Makefile
index 4ac9244..74e7b68 100644
--- a/Makefile
+++ b/Makefile
@@ -136,7 +136,7 @@ bindable.o: bindable.c bindable.h buffer.h estruct.h line.h utf8.h \
  retcode.h display.h edef.h file.h input.h
 buffer.o: buffer.c buffer.h estruct.h line.h utf8.h retcode.h display.h \
  edef.h file.h input.h window.h
-crypt.o: crypt.c crypt.h estruct.h line.h utf8.h retcode.h
+crypt.o: crypt.c estruct.h line.h utf8.h retcode.h crypt.h
 display.o: display.c display.h estruct.h line.h utf8.h retcode.h edef.h \
  termio.h version.h wrapper.h window.h
 ebind.o: ebind.c ebind.h basic.h bind.h edef.h estruct.h line.h utf8.h \
@@ -149,9 +149,9 @@ exec.o: exec.c exec.h estruct.h line.h utf8.h retcode.h buffer.h bind.h \
  edef.h display.h eval.h file.h flook.h input.h
 execute.o: execute.c edef.h estruct.h line.h utf8.h retcode.h bind.h \
  random.h display.h file.h
-file.o: file.c file.h buffer.h estruct.h line.h utf8.h retcode.h crypt.h \
+file.o: file.c estruct.h line.h utf8.h retcode.h file.h buffer.h crypt.h \
  edef.h execute.h fileio.h input.h lock.h log.h window.h
-fileio.o: fileio.c fileio.h retcode.h estruct.h line.h utf8.h crypt.h
+fileio.o: fileio.c estruct.h line.h utf8.h retcode.h fileio.h crypt.h
 flook.o: flook.c flook.h retcode.h estruct.h line.h utf8.h fileio.h
 globals.o: globals.c estruct.h line.h utf8.h retcode.h edef.h
 ibmpc.o: ibmpc.c estruct.h line.h utf8.h retcode.h edef.h
diff --git a/crypt.c b/crypt.c
index 3384410..bd98014 100644
--- a/crypt.c
+++ b/crypt.c
@@ -1,5 +1,7 @@
 /* crypt.c -- implements crypt.h */
 
+#include "estruct.h"
+
 #include "crypt.h"
 
 /*	CRYPT.C
diff --git a/crypt.h b/crypt.h
index 7cfbaca..dd7bea3 100644
--- a/crypt.h
+++ b/crypt.h
@@ -1,9 +1,9 @@
 #ifndef _CRYPT_H_
 #define _CRYPT_H_
 
-#include "estruct.h"
-
-#if CRYPT
+#ifndef CRYPT
+#error CRYPT should be defined
+#elif CRYPT
 void myencrypt( char *bptr, unsigned len) ;
 #endif
 
diff --git a/file.c b/file.c
index 40f8990..371e2b6 100644
--- a/file.c
+++ b/file.c
@@ -1,5 +1,6 @@
 /* file.c -- implements file.h */
 
+#include "estruct.h"
 #include "file.h"
 
 /*  file.c
diff --git a/file.h b/file.h
index f2f1d55..f8ada9c 100644
--- a/file.h
+++ b/file.h
@@ -1,7 +1,9 @@
 #ifndef _FILE_H_
 #define _FILE_H_
 
-#if CRYPT
+#ifndef CRYPT
+#error CRYPT should be defined.
+#elif CRYPT
 void cryptbufferkey( struct buffer *bp) ;
 int  set_encryption_key( int f, int n) ;
 #endif
diff --git a/fileio.c b/fileio.c
index 2bcdf4d..5327070 100644
--- a/fileio.c
+++ b/fileio.c
@@ -1,5 +1,6 @@
 /* fileio.c -- implements fileio.h */
 
+#include "estruct.h"
 #include "fileio.h"
 
 /*  FILEIO.C
diff --git a/fileio.h b/fileio.h
index be60bdf..3afb4dc 100644
--- a/fileio.h
+++ b/fileio.h
@@ -18,7 +18,9 @@ typedef enum {
 #define FTYPE_MAC   4
 /*      FTYPE_MIXED [ 3, 5, 6, 7] */
 
-#if CRYPT
+#ifndef CRYPT
+#error CRYPT should be defined.
+#elif CRYPT
 extern boolean	is_crypted ;	/* currently encrypting?   */
 #endif