diff --git a/src/builtins/function.h b/src/builtins/function.h
index f96527e7e..50c1fd373 100644
--- a/src/builtins/function.h
+++ b/src/builtins/function.h
@@ -3,7 +3,6 @@
 #define FISH_BUILTIN_FUNCTION_H
 
 #include "../common.h"
-#include "../maybe.h"
 #include "../parse_tree.h"
 
 class parser_t;
diff --git a/src/builtins/return.cpp b/src/builtins/return.cpp
index a0c01e699..f4a77c39d 100644
--- a/src/builtins/return.cpp
+++ b/src/builtins/return.cpp
@@ -4,6 +4,8 @@
 #include "return.h"
 
 #include <cerrno>
+#include <cstdlib>
+#include <cmath>
 #include <deque>
 
 #include "../builtin.h"
diff --git a/src/common.h b/src/common.h
index 07fe2ccff..7fa7eb82f 100644
--- a/src/common.h
+++ b/src/common.h
@@ -17,6 +17,7 @@
 #include <cstdint>
 #include <cwchar>
 #include <functional>
+#include <initializer_list>
 #include <iterator>
 #include <memory>
 #include <mutex>
diff --git a/src/highlight.cpp b/src/highlight.cpp
index cfeed450c..456a56f12 100644
--- a/src/highlight.cpp
+++ b/src/highlight.cpp
@@ -3,7 +3,6 @@
 
 #include "highlight.h"
 
-#include <dirent.h>
 #include <errno.h>
 #include <sys/stat.h>
 #include <unistd.h>
@@ -11,7 +10,7 @@
 #include <algorithm>
 #include <climits>
 #include <cwchar>
-#include <functional>
+#include <limits>
 #include <string>
 #include <unordered_map>
 #include <unordered_set>
diff --git a/src/parse_util.cpp b/src/parse_util.cpp
index f62a0e707..ba503eb73 100644
--- a/src/parse_util.cpp
+++ b/src/parse_util.cpp
@@ -10,6 +10,7 @@
 
 #include <algorithm>
 #include <cwchar>
+#include <cwctype>
 #include <memory>
 #include <string>
 #include <utility>
diff --git a/src/parser.h b/src/parser.h
index 1ad0c7ecf..9d002b329 100644
--- a/src/parser.h
+++ b/src/parser.h
@@ -14,7 +14,6 @@
 
 #include "common.h"
 #include "env.h"
-#include "event.h"
 #include "expand.h"
 #include "job_group.h"
 #include "maybe.h"
@@ -25,6 +24,7 @@
 #include "util.h"
 #include "wait_handle.h"
 
+struct event_t;
 class io_chain_t;
 class autoclose_fd_t;
 
diff --git a/src/tinyexpr.cpp b/src/tinyexpr.cpp
index 0900a1260..fca09613e 100644
--- a/src/tinyexpr.cpp
+++ b/src/tinyexpr.cpp
@@ -23,6 +23,8 @@
  */
 
 // This version has been altered and ported to C++ for inclusion in fish.
+#include "config.h"
+
 #include "tinyexpr.h"
 
 #include <ctype.h>
diff --git a/src/tokenizer.cpp b/src/tokenizer.cpp
index 528d6e68c..42d0264fc 100644
--- a/src/tokenizer.cpp
+++ b/src/tokenizer.cpp
@@ -10,6 +10,7 @@
 #include <wctype.h>
 
 #include <cwchar>
+#include <utility>
 #include <vector>
 
 #include "common.h"
diff --git a/src/wildcard.cpp b/src/wildcard.cpp
index 6d66a8216..4e81670fc 100644
--- a/src/wildcard.cpp
+++ b/src/wildcard.cpp
@@ -4,7 +4,6 @@
 
 #include "wildcard.h"
 
-#include <dirent.h>
 #include <errno.h>
 #include <stdint.h>
 #include <sys/stat.h>
diff --git a/src/wutil.h b/src/wutil.h
index eacb1093e..378dbd5d4 100644
--- a/src/wutil.h
+++ b/src/wutil.h
@@ -11,7 +11,7 @@
 #include <sys/types.h>
 #ifdef __APPLE__
 // This include is required on macOS 10.10 for locale_t
-#include <xlocale.h>
+#include <xlocale.h> // IWYU pragma: keep
 #endif
 
 #include <ctime>