diff --git a/configure.ac b/configure.ac
index 860cbb4a..988e32e5 100644
--- a/configure.ac
+++ b/configure.ac
@@ -479,7 +479,6 @@ AC_CHECK_HEADERS([sys/types.h])
 AC_CHECK_HEADERS([stdint.h])
 AC_CHECK_HEADERS([inttypes.h])
 AC_CHECK_HEADERS([time.h])
-AC_CHECK_HEADERS([ansidecl.h])
 AC_CHECK_HEADERS([math.h])
 AC_CHECK_HEADERS([limits.h])
 AC_CHECK_HEADERS([float.h])
diff --git a/include/libxml/xmlversion.h.in b/include/libxml/xmlversion.h.in
index b173be9e..d10f9754 100644
--- a/include/libxml/xmlversion.h.in
+++ b/include/libxml/xmlversion.h.in
@@ -410,9 +410,6 @@ XMLPUBFUN void XMLCALL xmlCheckVersion(int version);
 #endif
 
 #ifdef __GNUC__
-#ifdef HAVE_ANSIDECL_H
-#include <ansidecl.h>
-#endif
 
 /**
  * ATTRIBUTE_UNUSED:
diff --git a/include/libxml/xmlwin32version.h b/include/libxml/xmlwin32version.h
index 96412411..e0f2b389 100644
--- a/include/libxml/xmlwin32version.h
+++ b/include/libxml/xmlwin32version.h
@@ -214,9 +214,6 @@ extern void xmlCheckVersion(int version);
  * Macro used to signal to GCC unused function parameters
  */
 #ifdef __GNUC__
-#ifdef HAVE_ANSIDECL_H
-#include <ansidecl.h>
-#endif
 #ifndef ATTRIBUTE_UNUSED
 #define ATTRIBUTE_UNUSED
 #endif
diff --git a/include/libxml/xmlwin32version.h.in b/include/libxml/xmlwin32version.h.in
index 375f3a4e..2176ad11 100644
--- a/include/libxml/xmlwin32version.h.in
+++ b/include/libxml/xmlwin32version.h.in
@@ -243,9 +243,6 @@ extern void xmlCheckVersion(int version);
 #endif
 
 #ifdef __GNUC__
-#ifdef HAVE_ANSIDECL_H
-#include <ansidecl.h>
-#endif
 
 /**
  * ATTRIBUTE_UNUSED:
diff --git a/macos/src/config-mac.h b/macos/src/config-mac.h
index 3e1606d6..ca6f9939 100644
--- a/macos/src/config-mac.h
+++ b/macos/src/config-mac.h
@@ -57,9 +57,6 @@
 /* Define if you have the vsprintf function.  */
 #define HAVE_VSPRINTF
 
-/* Define if you have the <ansidecl.h> header file.  */
-#define HAVE_ANSIDECL_H
-
 /* Define if you have the <arpa/inet.h> header file.  */
 #define HAVE_ARPA_INET_H
 
diff --git a/os400/os400config.h.in b/os400/os400config.h.in
index 18c00834..1840c17c 100644
--- a/os400/os400config.h.in
+++ b/os400/os400config.h.in
@@ -6,9 +6,6 @@
 ***     Author: Patrick Monnerat <pm@datasphere.ch>, DATASPHERE S.A.
 **/
 
-/* Define to 1 if you have the <ansidecl.h> header file. */
-#undef HAVE_ANSIDECL_H
-
 /* Define to 1 if you have the <arpa/inet.h> header file. */
 #define HAVE_ARPA_INET_H        1