diff --git a/.github/scripts/cmp-config.pl b/.github/scripts/cmp-config.pl
index b697ae1203..a0d33498a7 100755
--- a/.github/scripts/cmp-config.pl
+++ b/.github/scripts/cmp-config.pl
@@ -88,6 +88,7 @@ my %remove = (
     '#define PACKAGE_TARNAME "curl"' => 1,
     '#define PACKAGE_URL ""' => 1,
     '#define PACKAGE_VERSION "-"' => 1,
+    '#define STDC_HEADERS 1' => 1,
     '#define VERSION "-"' => 1,
     '#define _FILE_OFFSET_BITS 64' => 1,
     );
diff --git a/CMake/CurlTests.c b/CMake/CurlTests.c
index 95cd89bb63..c9d0b93d21 100644
--- a/CMake/CurlTests.c
+++ b/CMake/CurlTests.c
@@ -114,16 +114,6 @@ int main(void)
 }
 #endif
 
-#ifdef STDC_HEADERS
-#include <stdlib.h>
-#include <stdarg.h>
-#include <string.h>
-int main(void)
-{
-  return 0;
-}
-#endif
-
 #ifdef HAVE_FILE_OFFSET_BITS
 #include <sys/types.h>
 /* Check that off_t can represent 2**63 - 1 correctly.
diff --git a/CMake/unix-cache.cmake b/CMake/unix-cache.cmake
index 97be36d5f3..287c3fdf9e 100644
--- a/CMake/unix-cache.cmake
+++ b/CMake/unix-cache.cmake
@@ -314,5 +314,4 @@ set(HAVE_UTIME 1)
 set(HAVE_UTIMES 1)
 set(HAVE_UTIME_H 1)
 set(HAVE_WRITABLE_ARGV 1)
-set(STDC_HEADERS 1)
 set(USE_UNIX_SOCKETS 1)
diff --git a/CMake/win32-cache.cmake b/CMake/win32-cache.cmake
index c108087273..a684b459b0 100644
--- a/CMake/win32-cache.cmake
+++ b/CMake/win32-cache.cmake
@@ -161,7 +161,6 @@ set(HAVE_TERMIO_H 0)
 set(HAVE_TIME_T_UNSIGNED 0)
 set(HAVE_UTIME 1)
 set(HAVE_UTIMES 0)
-set(STDC_HEADERS 1)
 
 # Types and sizes
 
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 5929b741ce..5aa412fc98 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1731,7 +1731,6 @@ foreach(_curl_test IN ITEMS
     HAVE_GETHOSTBYNAME_R_5
     HAVE_GETHOSTBYNAME_R_6
     HAVE_BOOL_T
-    STDC_HEADERS
     HAVE_ATOMIC
 )
   curl_internal_test(${_curl_test})
diff --git a/lib/config-os400.h b/lib/config-os400.h
index 76841af202..050fd9d7da 100644
--- a/lib/config-os400.h
+++ b/lib/config-os400.h
@@ -238,11 +238,6 @@
 /* Size of time_t in number of bytes */
 #define SIZEOF_TIME_T           4
 
-/* Define to 1 if all of the C89 standard headers exist (not only the ones
-   required in a freestanding environment). This macro is provided for
-   backward compatibility; new code need not use it. */
-#define STDC_HEADERS            1
-
 /* Define if you want to enable IPv6 support */
 #define USE_IPV6
 
diff --git a/lib/config-win32.h b/lib/config-win32.h
index fedfb8f30e..1f4f12f433 100644
--- a/lib/config-win32.h
+++ b/lib/config-win32.h
@@ -71,9 +71,6 @@
 /*                        OTHER HEADER INFO                         */
 /* ---------------------------------------------------------------- */
 
-/* Define if you have the ANSI C header files. */
-#define STDC_HEADERS 1
-
 /* Define to 1 if bool is an available type. */
 #if (defined(_MSC_VER) && (_MSC_VER >= 1800)) || defined(__MINGW32__)
 #define HAVE_BOOL_T 1
diff --git a/lib/curl_config-cmake.h.in b/lib/curl_config-cmake.h.in
index 92280010c0..add3b26aad 100644
--- a/lib/curl_config-cmake.h.in
+++ b/lib/curl_config-cmake.h.in
@@ -634,9 +634,6 @@ ${SIZEOF_SIZE_T_CODE}
 /* The size of `time_t', as computed by sizeof. */
 ${SIZEOF_TIME_T_CODE}
 
-/* Define to 1 if you have the ANSI C header files. */
-#cmakedefine STDC_HEADERS 1
-
 /* Define if you have POSIX pthreads */
 #cmakedefine HAVE_THREADS_POSIX 1
 
diff --git a/lib/curl_setup.h b/lib/curl_setup.h
index a26bb23cb2..065fd04dde 100644
--- a/lib/curl_setup.h
+++ b/lib/curl_setup.h
@@ -490,10 +490,6 @@
 #  endif
 #endif
 
-#ifndef STDC_HEADERS /* no standard C headers! */
-#include <curl/stdcheaders.h>
-#endif
-
 #include <stdint.h>
 #define HAVE_UINTPTR_T  /* assume uintptr_t is provided by stdint.h */
 
diff --git a/projects/vms/config_h.com b/projects/vms/config_h.com
index 0b23cc6633..2de76ad731 100644
--- a/projects/vms/config_h.com
+++ b/projects/vms/config_h.com
@@ -1648,16 +1648,6 @@ $           write tf "#endif"
 $           goto cfgh_in_loop1
 $       endif
 $!
-$!      Process STDC_HEADERS (SAMBA!)
-$!---------------------------
-$       if key2 .eqs. "STDC_HEADERS"
-$       then
-$           write tf "#ifndef STDC_HEADERS"
-$           write tf "#define STDC_HEADERS 1"
-$           write tf "#endif"
-$           goto cfgh_in_loop1
-$       endif
-$!
 $!      Process PROTOTYPES directive
 $!-------------------------------------
 $       if key2 .eqs. "PROTOTYPES"