diff --git a/src/core/context.c b/src/core/context.c
index c60510e..c7dd6e2 100644
--- a/src/core/context.c
+++ b/src/core/context.c
@@ -11,14 +11,15 @@
 #include <signal.h>
 #include "context.h"
 
-extern struct BotXmppCtx *g_bctx = NULL;
+/* static lifetime but only accessible here and through get and set functions below */
+static struct BotXmppCtx *g_bctx = NULL;
 
 struct BotXmppCtx *bot_get_ctx()
 {
     return g_bctx;
 }
 
-void bot_set_ctx(struct BotXmppCtx *ctx)
+void bot_set_ctx(struct BotXmppCtx * const ctx)
 {
     if(g_bctx) {
         fprintf(stderr, "Dev error: cannot set XMPP ctx twice in the same program run.\n");
@@ -137,7 +138,7 @@
     return 0;
 }
 
-int bot_xmpp_startup(struct BotUserInfo user, GString *avatarFile)
+int bot_xmpp_startup(const struct BotUserInfo user, GString * const avatarFile)
 {
     xmpp_log_t* newLog;
     xmpp_ctx_t* newCtx;
diff --git a/src/core/context.h b/src/core/context.h
index f53f584..d0d25b8 100644
--- a/src/core/context.h
+++ b/src/core/context.h
@@ -8,24 +8,24 @@
 #pragma once
 #include "handlers.h"
 
-struct BotUserInfo {
+typedef struct BotUserInfo {
     GString* jid;
     GString* pass;
-};
+} BotUserInfo;
 
-struct BotXmppCtx {
+typedef struct BotXmppCtx {
     xmpp_log_t* log;
     xmpp_ctx_t* ctx;
     xmpp_conn_t* conn;
-};
+} BotXmppCtx;
 
-void bot_free_user_data(struct BotUserInfo user, GString *filename, bool freeSegment);
+void bot_free_user_data(const BotUserInfo user, GString *filename, bool freeSegment);
 
 /* sets the given avatar file (base64 encoded) */
-int bot_xmpp_set_avatar(struct BotXmppCtx * const bctx, const GString *avatarFile);
+int bot_xmpp_set_avatar(BotXmppCtx * const bctx, const GString *avatarFile);
 
 /* perform xmpp startup, store in bctx if completed successfully */
-int bot_xmpp_startup(struct BotUserInfo user, GString *avatarFile);
+int bot_xmpp_startup(const BotUserInfo user, GString * const avatarFile);
 
 /* teardown and free ctx and connection in bctx */
 void bot_xmpp_shutdown();
@@ -33,7 +33,6 @@
 /* send a reminder when SIGALARM is triggered */
 void bot_reminder_alarm_func(int s);
 
-/* global context for signal handling */
-extern struct BotXmppCtx *g_bctx;
-struct BotXmppCtx *bot_get_ctx();
-void bot_set_ctx(struct BotXmppCtx *bctx);
+/* static-lifetime context for signal handling */
+BotXmppCtx *bot_get_ctx();
+void bot_set_ctx(BotXmppCtx * const bctx);
diff --git a/src/expenses/types.c b/src/expenses/types.c
index e467a63..e99c163 100644
--- a/src/expenses/types.c
+++ b/src/expenses/types.c
@@ -7,10 +7,11 @@
 #include <glib.h>
 #include "types.h"
 
-extern BotCommand g_LastCommand = BOT_CMD_NONE;
-extern BotExpenseEntry *g_LastExpenseEntry = NULL;
-extern BotReminder *g_LastReminder = NULL;
-extern GString *g_filename = NULL;
+/* static lifetime but only accessible here and through get and set functions below */
+static BotCommand g_LastCommand = BOT_CMD_NONE;
+static BotExpenseEntry *g_LastExpenseEntry = NULL;
+static BotReminder *g_LastReminder = NULL;
+static GString *g_filename = NULL;
 
 BotCommand bot_get_last_command()
 {
diff --git a/src/expenses/types.h b/src/expenses/types.h
index 9899731..7731f0b 100644
--- a/src/expenses/types.h
+++ b/src/expenses/types.h
@@ -73,21 +73,17 @@
  );
 
 /* use this to check the last received command when responding */
-extern BotCommand g_LastCommand;
 BotCommand bot_get_last_command();
 void bot_set_last_command(BotCommand cmd);
 
 /* store the last expense in memory */
-extern BotExpenseEntry *g_LastExpenseEntry;
 BotExpenseEntry *bot_get_last_expense();
 void bot_set_last_expense(BotExpenseEntry *entry);
 
 /* store the last reminder in memory */
-extern BotReminder *g_LastReminder;
 BotReminder *bot_get_last_reminder();
 void bot_set_last_reminder(BotReminder *reminder);
 
 /* store the filename in memory */
-extern GString *g_filename;
 GString *bot_get_filename();
 void bot_set_filename(GString *fn);