diff --git a/alias/dlgalias.c b/alias/dlgalias.c
index 6b16e8a6f4e..3b7838358dc 100644
--- a/alias/dlgalias.c
+++ b/alias/dlgalias.c
@@ -45,7 +45,6 @@
 #include "format_flags.h"
 #include "gui.h"
 #include "keymap.h"
-#include "mutt_globals.h"
 #include "mutt_menu.h"
 #include "muttlib.h"
 #include "opcodes.h"
diff --git a/alternates.c b/alternates.c
index aa942b1802c..dbf44ae3b92 100644
--- a/alternates.c
+++ b/alternates.c
@@ -30,21 +30,16 @@
 #include <stdbool.h>
 #include <stdint.h>
 #include <stdio.h>
-#include <string.h>
 #include "mutt/lib.h"
-#include "config/lib.h"
+#include "address/lib.h"
 #include "email/lib.h"
 #include "core/lib.h"
-#include "gui/lib.h"
 #include "mutt.h"
 #include "alternates.h"
-#include "ncrypt/lib.h"
 #include "attachments.h"
 #include "command_parse.h"
 #include "init.h"
 #include "mutt_commands.h"
-#include "mutt_globals.h"
-#include "mx.h"
 
 struct RegexList Alternates = STAILQ_HEAD_INITIALIZER(Alternates); ///< List of regexes to match the user's alternate email addresses
 struct RegexList UnAlternates = STAILQ_HEAD_INITIALIZER(UnAlternates); ///< List of regexes to blacklist false matches in Alternates
diff --git a/alternates.h b/alternates.h
index a53a24ccd5a..7ac0361f702 100644
--- a/alternates.h
+++ b/alternates.h
@@ -27,6 +27,9 @@
 #include <stdint.h>
 #include "mutt_commands.h"
 
+struct Buffer;
+struct Mailbox;
+
 /**
  * enum NotifyAlternates - Alternates command notification types
  */
diff --git a/attachments.c b/attachments.c
index b959319d477..8799b1fee48 100644
--- a/attachments.c
+++ b/attachments.c
@@ -41,7 +41,6 @@
 #include "ncrypt/lib.h"
 #include "init.h"
 #include "mutt_commands.h"
-#include "mutt_globals.h"
 #include "mx.h"
 
 /**
diff --git a/commands.c b/commands.c
index a5776eee052..144fe17b683 100644
--- a/commands.c
+++ b/commands.c
@@ -62,7 +62,6 @@
 #include "mutt_globals.h"
 #include "mutt_logging.h"
 #include "mutt_mailbox.h"
-#include "mutt_menu.h"
 #include "muttlib.h"
 #include "mx.h"
 #include "options.h"
diff --git a/commands.h b/commands.h
index 901e1ea0ce8..d91fb5ad460 100644
--- a/commands.h
+++ b/commands.h
@@ -25,7 +25,6 @@
 
 #include <stdbool.h>
 #include <stdio.h>
-#include "mutt_menu.h"
 
 struct Body;
 struct Email;
diff --git a/gui/curs_lib.h b/gui/curs_lib.h
index ae3fdf6c66b..7ef0dc5724f 100644
--- a/gui/curs_lib.h
+++ b/gui/curs_lib.h
@@ -29,10 +29,10 @@
 #include "mutt.h"
 #include "browser.h"
 #include "keymap.h"
-#include "pager/lib.h"
 
 struct Buffer;
 struct Mailbox;
+struct PagerView;
 
 extern int MuttGetchTimeout; ///< Timeout in ms for mutt_getch()
 
diff --git a/gui/dialog.c b/gui/dialog.c
index 575a2fc7409..ee63a2058d4 100644
--- a/gui/dialog.c
+++ b/gui/dialog.c
@@ -34,6 +34,7 @@
 #include "core/lib.h"
 #include "debug/lib.h"
 #include "lib.h"
+#include "keymap.h"
 #include "mutt_menu.h"
 
 /**
diff --git a/init.c b/init.c
index a6b55662644..4d552ea0fe6 100644
--- a/init.c
+++ b/init.c
@@ -29,7 +29,6 @@
 
 #include "config.h"
 #include <ctype.h>
-#include <inttypes.h>
 #include <pwd.h>
 #include <stdbool.h>
 #include <stdio.h>
@@ -59,7 +58,6 @@
 #ifdef USE_LUA
 #include "mutt_lua.h"
 #endif
-#include "attachments.h"
 #include "mutt_menu.h"
 #include "muttlib.h"
 #include "myvar.h"
diff --git a/main.c b/main.c
index 7037c645c03..61ed961e456 100644
--- a/main.c
+++ b/main.c
@@ -71,7 +71,6 @@
 #include "mutt_history.h"
 #include "mutt_logging.h"
 #include "mutt_mailbox.h"
-#include "mutt_menu.h"
 #include "muttlib.h"
 #include "mx.h"
 #include "myvar.h"
diff --git a/mutt_attach.c b/mutt_attach.c
index aa553183cea..3193b1a61e1 100644
--- a/mutt_attach.c
+++ b/mutt_attach.c
@@ -45,7 +45,6 @@
 #include "ncrypt/lib.h"
 #include "pager/lib.h"
 #include "send/lib.h"
-#include "context.h"
 #include "copy.h"
 #include "handler.h"
 #include "mailcap.h"
diff --git a/mx.c b/mx.c
index c1f9932f765..80f03147d0b 100644
--- a/mx.c
+++ b/mx.c
@@ -60,7 +60,6 @@
 #include "opcodes.h"
 #include "options.h"
 #include "protos.h"
-#include "sort.h"
 #ifdef USE_COMP_MBOX
 #include "compmbox/lib.h"
 #endif
diff --git a/ncrypt/crypt.c b/ncrypt/crypt.c
index 25e076cee42..6914eeeac01 100644
--- a/ncrypt/crypt.c
+++ b/ncrypt/crypt.c
@@ -49,11 +49,9 @@
 #include "lib.h"
 #include "send/lib.h"
 #include "attachments.h"
-#include "context.h"
 #include "copy.h"
 #include "cryptglue.h"
 #include "handler.h"
-#include "mutt_globals.h"
 #include "muttlib.h"
 #include "options.h"
 #ifdef USE_AUTOCRYPT
diff --git a/ncrypt/cryptglue.c b/ncrypt/cryptglue.c
index 201592656c2..0b9d71048a7 100644
--- a/ncrypt/cryptglue.c
+++ b/ncrypt/cryptglue.c
@@ -62,7 +62,6 @@ struct Envelope;
 
 struct Address;
 struct AddressList;
-struct State;
 
 #ifdef CRYPT_BACKEND_CLASSIC_PGP
 extern struct CryptModuleSpecs CryptModPgpClassic;
diff --git a/ncrypt/pgp.h b/ncrypt/pgp.h
index 86fba429a4c..e49e6c88b54 100644
--- a/ncrypt/pgp.h
+++ b/ncrypt/pgp.h
@@ -33,6 +33,7 @@
 struct AddressList;
 struct Body;
 struct Email;
+struct Mailbox;
 struct PgpKeyInfo;
 struct State;
 
diff --git a/notmuch/config.c b/notmuch/config.c
index e0c89cf7d60..3a74c8c3534 100644
--- a/notmuch/config.c
+++ b/notmuch/config.c
@@ -36,7 +36,7 @@
 
 /**
  * is_valid_notmuch_url - Checks that a URL is in required form.
- * @retval true url in form notmuch://<absolute path>
+ * @retval true url in form notmuch://[absolute path]
  * @retval false url is not in required form.
  */
 static bool is_valid_notmuch_url(const char *url)
@@ -45,14 +45,16 @@ static bool is_valid_notmuch_url(const char *url)
 }
 
 /**
- * nm_default_url_validator - Ensure nm_default_url is of the form notmuch://<absolute path> - Implements ConfigDef::validator()
+ * nm_default_url_validator - Ensure nm_default_url is of the form notmuch://[absolute path] - Implements ConfigDef::validator()
  */
-static int nm_default_url_validator(const struct ConfigSet *cs, const struct ConfigDef *cdef, intptr_t value, struct Buffer *err)
+static int nm_default_url_validator(const struct ConfigSet *cs, const struct ConfigDef *cdef,
+                                    intptr_t value, struct Buffer *err)
 {
   const char *url = (const char *) value;
   if (!is_valid_notmuch_url(url))
   {
-    mutt_buffer_printf(err, _("nm_default_url must be: notmuch://<absolute path> . Current: %s"), url);
+    mutt_buffer_printf(
+        err, _("nm_default_url must be: notmuch://<absolute path> . Current: %s"), url);
     return CSR_ERR_INVALID;
   }
 
diff --git a/protos.h b/protos.h
index 7eb960fee60..c33586c549a 100644
--- a/protos.h
+++ b/protos.h
@@ -33,7 +33,6 @@
 #include "ncrypt/lib.h"
 #include "keymap.h"
 
-struct Context;
 struct Email;
 struct EmailList;
 struct EnterState;
diff --git a/recvattach.c b/recvattach.c
index ec4925aefb3..a4612b5e4fa 100644
--- a/recvattach.c
+++ b/recvattach.c
@@ -52,7 +52,6 @@
 #include "keymap.h"
 #include "mailcap.h"
 #include "mutt_attach.h"
-#include "mutt_globals.h"
 #include "mutt_menu.h"
 #include "mutt_thread.h"
 #include "muttlib.h"
diff --git a/recvattach.h b/recvattach.h
index 440b19d73a1..961a93dad23 100644
--- a/recvattach.h
+++ b/recvattach.h
@@ -33,6 +33,7 @@
 struct AttachCtx;
 struct Body;
 struct Email;
+struct Mailbox;
 
 void mutt_attach_init(struct AttachCtx *actx);
 void mutt_update_tree(struct AttachCtx *actx);
diff --git a/send/send.h b/send/send.h
index 67d41a10bc2..675d7b2c5ba 100644
--- a/send/send.h
+++ b/send/send.h
@@ -30,7 +30,6 @@
 struct AddressList;
 struct Body;
 struct ConfigSubset;
-struct Context;
 struct Email;
 struct EmailList;
 struct Envelope;
diff --git a/send/sendlib.c b/send/sendlib.c
index 888d19dc088..626ecd43322 100644
--- a/send/sendlib.c
+++ b/send/sendlib.c
@@ -49,7 +49,6 @@
 #include "lib.h"
 #include "ncrypt/lib.h"
 #include "attachments.h"
-#include "context.h"
 #include "copy.h"
 #include "handler.h"
 #include "mutt_globals.h"
diff --git a/sort.c b/sort.c
index 9375812cab4..570aa883fde 100644
--- a/sort.c
+++ b/sort.c
@@ -38,7 +38,6 @@
 #include "core/lib.h"
 #include "alias/lib.h"
 #include "sort.h"
-#include "mutt_globals.h"
 #include "mutt_logging.h"
 #include "mutt_thread.h"
 #include "mx.h"
diff --git a/sort.h b/sort.h
index 21baab2b9f2..ecc2e0a4f92 100644
--- a/sort.h
+++ b/sort.h
@@ -31,7 +31,6 @@
 #include "options.h" // IWYU pragma: keep
 
 struct Address;
-struct Mailbox;
 struct ThreadsContext;
 
 /**
diff --git a/subjectrx.c b/subjectrx.c
index 7391f81d526..67a0f3b3179 100644
--- a/subjectrx.c
+++ b/subjectrx.c
@@ -27,10 +27,12 @@
  */
 
 #include "config.h"
+#include <stddef.h>
 #include <stdint.h>
 #include "mutt/lib.h"
 #include "email/lib.h"
 #include "core/lib.h"
+#include "mutt.h"
 #include "subjectrx.h"
 #include "init.h"
 #include "mutt_commands.h"
diff --git a/subjectrx.h b/subjectrx.h
index b3eea63f77b..520d89261a0 100644
--- a/subjectrx.h
+++ b/subjectrx.h
@@ -28,6 +28,7 @@
 #include "mutt_commands.h"
 
 struct Buffer;
+struct Envelope;
 struct Mailbox;
 
 /**