diff --git a/ConfigureChecks.cmake b/ConfigureChecks.cmake
index 6ef2c47..5c04d05 100644
--- a/ConfigureChecks.cmake
+++ b/ConfigureChecks.cmake
@@ -152,7 +152,6 @@ check_type_size("signed long" SIZEOF_SIGNED_LONG)
 check_type_size("signed long long" SIZEOF_SIGNED_LONG_LONG)
 
 check_function_exists(chdir HAVE_CHDIR)
-check_function_exists(difftime HAVE_DIFFTIME)
 check_function_exists(epoll_create HAVE_EPOLL_CREATE)
 check_function_exists(fork HAVE_FORK)
 check_function_exists(ftime HAVE_FTIME)
@@ -166,7 +165,6 @@ check_function_exists(getpwnam HAVE_GETPWNAME)
 check_function_exists(getrlimit HAVE_GETRLIMIT)
 check_function_exists(gettimeofday HAVE_GETTIMEOFDAY)
 check_function_exists(getuid HAVE_GETUID)
-check_function_exists(index HAVE_INDEX)
 check_function_exists(ioctl HAVE_IOCTL)
 check_function_exists(kqueue HAVE_KQUEUE)
 check_function_exists(_mkdir HAVE__MKDIR)
@@ -174,7 +172,6 @@ check_function_exists(mkdir HAVE_MKDIR)
 check_function_exists(mmap HAVE_MMAP)
 check_function_exists(pipe HAVE_PIPE)
 check_function_exists(poll HAVE_POLL)
-check_function_exists(rindex HAVE_RINDEX)
 check_function_exists(setitimer HAVE_SETITIMER)
 check_function_exists(setpgid HAVE_SETPGID)
 check_function_exists(setpgrp HAVE_SETPGRP)
@@ -184,12 +181,10 @@ check_function_exists(sigaction HAVE_SIGACTION)
 check_function_exists(sigaddset HAVE_SIGADDSET)
 check_function_exists(sigprocmask HAVE_SIGPROCMASK)
 check_function_exists(strcasecmp HAVE_STRCASECMP)
-check_function_exists(strchr HAVE_STRCHR)
 check_function_exists(strdup HAVE_STRDUP)
 check_function_exists(stricmp HAVE_STRICMP)
 check_function_exists(strncasecmp HAVE_STRNCASECMP)
 check_function_exists(strnicmp HAVE_STRNICMP)
-check_function_exists(strrchr HAVE_STRRCHR)
 check_function_exists(strsep HAVE_STRSEP)
 check_function_exists(strtoul HAVE_STRTOUL)
 check_function_exists(uname HAVE_UNAME)
diff --git a/config.h.cmake b/config.h.cmake
index 4deb897..b10c542 100644
--- a/config.h.cmake
+++ b/config.h.cmake
@@ -73,11 +73,6 @@
 #cmakedefine HAVE_STRICMP
 #cmakedefine HAVE_STRNICMP
 #cmakedefine HAVE_CHDIR
-#cmakedefine HAVE_DIFFTIME
-#cmakedefine HAVE_STRCHR
-#cmakedefine HAVE_STRRCHR
-#cmakedefine HAVE_INDEX
-#cmakedefine HAVE_RINDEX
 #cmakedefine HAVE_WAIT
 #cmakedefine HAVE_WAITPID
 #cmakedefine HAVE_PIPE