diff --git a/libc/src/string/memchr.h b/libc/src/string/memchr.h
--- a/libc/src/string/memchr.h
+++ b/libc/src/string/memchr.h
@@ -9,7 +9,7 @@
 #ifndef LLVM_LIBC_SRC_STRING_MEMCHR_H
 #define LLVM_LIBC_SRC_STRING_MEMCHR_H
 
-#include <stddef.h>
+#include <stddef.h> // size_t
 
 namespace __llvm_libc {
 
diff --git a/libc/src/string/memrchr.h b/libc/src/string/memrchr.h
--- a/libc/src/string/memrchr.h
+++ b/libc/src/string/memrchr.h
@@ -9,7 +9,7 @@
 #ifndef LLVM_LIBC_SRC_STRING_MEMRCHR_H
 #define LLVM_LIBC_SRC_STRING_MEMRCHR_H
 
-#include <stddef.h>
+#include <stddef.h> // size_t
 
 namespace __llvm_libc {
 
diff --git a/libc/src/string/strcat.h b/libc/src/string/strcat.h
--- a/libc/src/string/strcat.h
+++ b/libc/src/string/strcat.h
@@ -9,8 +9,6 @@
 #ifndef LLVM_LIBC_SRC_STRING_STRCAT_H
 #define LLVM_LIBC_SRC_STRING_STRCAT_H
 
-#include <string.h>
-
 namespace __llvm_libc {
 
 char *strcat(char *__restrict dest, const char *__restrict src);
diff --git a/libc/src/string/strcpy.h b/libc/src/string/strcpy.h
--- a/libc/src/string/strcpy.h
+++ b/libc/src/string/strcpy.h
@@ -9,8 +9,6 @@
 #ifndef LLVM_LIBC_SRC_STRING_STRCPY_H
 #define LLVM_LIBC_SRC_STRING_STRCPY_H
 
-#include <string.h>
-
 namespace __llvm_libc {
 
 char *strcpy(char *__restrict dest, const char *__restrict src);
diff --git a/libc/src/string/strcspn.h b/libc/src/string/strcspn.h
--- a/libc/src/string/strcspn.h
+++ b/libc/src/string/strcspn.h
@@ -9,7 +9,7 @@
 #ifndef LLVM_LIBC_SRC_STRING_STRCSPN_H
 #define LLVM_LIBC_SRC_STRING_STRCSPN_H
 
-#include <stddef.h>
+#include <stddef.h> // size_t
 
 namespace __llvm_libc {
 
diff --git a/libc/src/string/strlen.h b/libc/src/string/strlen.h
--- a/libc/src/string/strlen.h
+++ b/libc/src/string/strlen.h
@@ -9,7 +9,7 @@
 #ifndef LLVM_LIBC_SRC_STRING_STRLEN_H
 #define LLVM_LIBC_SRC_STRING_STRLEN_H
 
-#include <string.h>
+#include <stddef.h> // size_t
 
 namespace __llvm_libc {
 
diff --git a/libc/src/string/strncpy.h b/libc/src/string/strncpy.h
--- a/libc/src/string/strncpy.h
+++ b/libc/src/string/strncpy.h
@@ -9,7 +9,7 @@
 #ifndef LLVM_LIBC_SRC_STRING_STRNCPY_H
 #define LLVM_LIBC_SRC_STRING_STRNCPY_H
 
-#include <stddef.h>
+#include <stddef.h> // size_t
 
 namespace __llvm_libc {
 
diff --git a/libc/src/string/strnlen.h b/libc/src/string/strnlen.h
--- a/libc/src/string/strnlen.h
+++ b/libc/src/string/strnlen.h
@@ -9,7 +9,7 @@
 #ifndef LLVM_LIBC_SRC_STRING_STRNLEN_H
 #define LLVM_LIBC_SRC_STRING_STRNLEN_H
 
-#include <stddef.h>
+#include <stddef.h> // size_t
 
 namespace __llvm_libc {
 
diff --git a/libc/src/string/strspn.h b/libc/src/string/strspn.h
--- a/libc/src/string/strspn.h
+++ b/libc/src/string/strspn.h
@@ -9,7 +9,7 @@
 #ifndef LLVM_LIBC_SRC_STRING_STRSPN_H
 #define LLVM_LIBC_SRC_STRING_STRSPN_H
 
-#include <stddef.h>
+#include <stddef.h> // size_t
 
 namespace __llvm_libc {