diff --git a/CMakeLists.txt b/CMakeLists.txt
index 41b69aeb..7e1aa08d 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -174,8 +174,6 @@ else()
 	check_function_exists(gettimeofday HAVE_GETTIMEOFDAY)
 	check_include_files(inttypes.h HAVE_INTTYPES_H)
 	check_function_exists(isascii HAVE_ISASCII)
-	check_function_exists(isinf HAVE_ISINF)
-	check_function_exists(isnan HAVE_ISNAN)
 	check_library_exists(history append_history "" HAVE_LIBHISTORY)
 	check_library_exists(readline readline "" HAVE_LIBREADLINE)
 	check_include_files(limits.h HAVE_LIMITS_H)
@@ -194,7 +192,6 @@ else()
 	check_function_exists(rand_r HAVE_RAND_R)
 	check_include_files(resolv.h HAVE_RESOLV_H)
 	check_library_exists(dld shl_load "" HAVE_SHLLOAD)
-	check_function_exists(signal HAVE_SIGNAL)
 	check_include_files(signal.h HAVE_SIGNAL_H)
 	check_function_exists(snprintf HAVE_SNPRINTF)
 	check_function_exists(sprintf HAVE_SPRINTF)
diff --git a/config.h.cmake.in b/config.h.cmake.in
index 61a8da12..e0935634 100644
--- a/config.h.cmake.in
+++ b/config.h.cmake.in
@@ -55,12 +55,6 @@
 /* Define to 1 if you have the `isascii' function. */
 #cmakedefine HAVE_ISASCII 1
 
-/* Define if isinf is there */
-#cmakedefine HAVE_ISINF 1
-
-/* Define if isnan is there */
-#cmakedefine HAVE_ISNAN 1
-
 /* Define if history library is there (-lhistory) */
 #cmakedefine HAVE_LIBHISTORY 1
 
@@ -120,9 +114,6 @@
 /* Have shl_load based dso */
 #cmakedefine HAVE_SHLLOAD 1
 
-/* Define to 1 if you have the `signal' function. */
-#cmakedefine HAVE_SIGNAL 1
-
 /* Define to 1 if you have the <signal.h> header file. */
 #cmakedefine HAVE_SIGNAL_H 1
 
diff --git a/configure.ac b/configure.ac
index 60bd2767..6e39605d 100644
--- a/configure.ac
+++ b/configure.ac
@@ -740,13 +740,6 @@ fi
 
 dnl ******************************End IPv6 checks******************************
 
-dnl Checks for isnan in libm if not in libc
-AC_CHECK_FUNC(isnan, AC_DEFINE([HAVE_ISNAN],[], [Define if isnan is there]) , AC_CHECK_LIB(m, isnan,
-  [AC_DEFINE([HAVE_ISNAN],[], [Define if isnan is there])]))
-
-AC_CHECK_FUNC(isinf, AC_DEFINE([HAVE_ISINF], [], [Define if isinf is there]) , AC_CHECK_LIB(m, isinf,
-  [AC_DEFINE([HAVE_ISINF], [], [Define if isinf is there])]))
-
 XML_LIBDIR='-L${libdir}'
 XML_INCLUDEDIR='-I${includedir}/libxml2'
 
@@ -1699,8 +1692,6 @@ AC_SUBST(ICONV_LIBS)
 AC_SUBST(ICU_LIBS)
 AC_SUBST(XML_INCLUDEDIR)
 AC_SUBST(HTML_DIR)
-AC_SUBST(HAVE_ISNAN)
-AC_SUBST(HAVE_ISINF)
 AC_SUBST(PYTHON)
 AC_SUBST(PYTHON_VERSION)
 AC_SUBST(PYTHON_INCLUDES)
diff --git a/macos/src/config-mac.h b/macos/src/config-mac.h
index cd49aba1..c82d2b9a 100644
--- a/macos/src/config-mac.h
+++ b/macos/src/config-mac.h
@@ -10,8 +10,6 @@
 #define VERSION
 
 #undef HAVE_LIBM
-#undef HAVE_ISINF
-#undef HAVE_ISNAN
 #undef HAVE_LIBHISTORY
 #undef HAVE_LIBREADLINE
 
@@ -28,9 +26,6 @@
 /* Define if you have the printf function.  */
 #define HAVE_PRINTF
 
-/* Define if you have the signal function.  */
-#define HAVE_SIGNAL
-
 /* Define if you have the snprintf function.  */
 #define HAVE_SNPRINTF
 
diff --git a/os400/os400config.h.in b/os400/os400config.h.in
index 322519f3..1588cfad 100644
--- a/os400/os400config.h.in
+++ b/os400/os400config.h.in
@@ -54,12 +54,6 @@
 /* Define to 1 if you have the `isascii' function. */
 #define HAVE_ISASCII            1
 
-/* Define if isinf is there */
-#undef HAVE_ISINF
-
-/* Define if isnan is there */
-#undef HAVE_ISNAN
-
 /* Define if history library is there (-lhistory) */
 #undef HAVE_LIBHISTORY
 
@@ -122,9 +116,6 @@
 /* Have shl_load based dso */
 #undef HAVE_SHLLOAD
 
-/* Define to 1 if you have the `signal' function. */
-#undef HAVE_SIGNAL
-
 /* Define to 1 if you have the <signal.h> header file. */
 #define HAVE_SIGNAL_H           1
 
diff --git a/vms/config.vms b/vms/config.vms
index 430c6d23..7f4342cd 100755
--- a/vms/config.vms
+++ b/vms/config.vms
@@ -11,10 +11,6 @@
 #undef PACKAGE
 #undef VERSION
 #undef HAVE_LIBM
-#undef HAVE_ISINF
-#if defined(_IEEE_FP) && (__CRTL_VER >= 60200000)
-# define HAVE_ISNAN 1
-#endif
 #undef HAVE_LIBHISTORY
 #undef HAVE_LIBREADLINE