--- a/src/global/mail_params.h	2020-01-21 10:52:36.025753878 +0300
+++ b/src/global/mail_params.h	2020-01-21 10:53:11.173763126 +0300
@@ -3983,23 +3983,23 @@
 
 #define VAR_TLSP_CLNT_USE_TLS		"tlsproxy_client_use_tls"
 #define DEF_TLSP_CLNT_USE_TLS		"$" VAR_SMTP_USE_TLS
-bool    var_tlsp_clnt_use_tls;
+extern bool    var_tlsp_clnt_use_tls;
 
 #define VAR_TLSP_CLNT_ENFORCE_TLS	"tlsproxy_client_enforce_tls"
 #define DEF_TLSP_CLNT_ENFORCE_TLS	"$" VAR_SMTP_ENFORCE_TLS
-bool    var_tlsp_clnt_enforce_tls;
+extern bool    var_tlsp_clnt_enforce_tls;
 
 #define VAR_TLSP_CLNT_LEVEL		"tlsproxy_client_level"
 #define DEF_TLSP_CLNT_LEVEL		"$" VAR_SMTP_TLS_LEVEL
-char   *var_tlsp_clnt_level;
+extern char   *var_tlsp_clnt_level;
 
 #define VAR_TLSP_CLNT_PER_SITE		"tlsproxy_client_per_site"
 #define DEF_TLSP_CLNT_PER_SITE		"$" VAR_SMTP_TLS_PER_SITE
-char   *var_tlsp_clnt_per_site;
+extern char   *var_tlsp_clnt_per_site;
 
 #define VAR_TLSP_CLNT_POLICY		"tlsproxy_client_policy"
 #define DEF_TLSP_CLNT_POLICY		"$" VAR_SMTP_TLS_POLICY
-char   *var_tlsp_clnt_policy;
+extern char   *var_tlsp_clnt_policy;
 
  /*
   * SMTPD "reject" contact info.
--- a/src/smtpd/smtpd_expand.h	2014-12-07 03:35:34.000000000 +0200
+++ b/src/smtpd/smtpd_expand.h	2020-01-21 11:30:10.270425259 +0300
@@ -18,7 +18,7 @@
  /*
   * External interface.
   */
-VSTRING *smtpd_expand_filter;
+extern VSTRING *smtpd_expand_filter;
 void    smtpd_expand_init(void);
 const char *smtpd_expand_lookup(const char *, int, void *);
 int     smtpd_expand(SMTPD_STATE *, VSTRING *, const char *, int);
--- a/src/trivial-rewrite/trivial-rewrite.h	2014-10-06 18:02:16.000000000 +0300
+++ b/src/trivial-rewrite/trivial-rewrite.h	2020-01-21 11:29:36.411409526 +0300
@@ -23,7 +23,7 @@
  /*
   * Connection management.
   */
-int     server_flags;
+extern int     server_flags;
 
  /*
   * rewrite.c
--- a/src/postconf/postconf.h	2018-02-19 04:43:29.000000000 +0300
+++ b/src/postconf/postconf.h	2020-01-21 11:29:07.851401023 +0300
@@ -152,7 +152,7 @@
   * Lookup table for master.cf entries. The table is terminated with an entry
   * that has a null argv member.
   */
-PCF_MASTER_ENT *pcf_master_table;
+extern PCF_MASTER_ENT *pcf_master_table;
 
  /*
   * Line-wrapping support.