diff --git a/config.h.in b/config.h.in
index dd6598aa98..6434b12646 100644
--- a/config.h.in
+++ b/config.h.in
@@ -159,6 +159,9 @@
 /* Define to 1 if you have the `FIPS_mode' function. */
 #undef HAVE_FIPS_MODE
 
+/* Define to 1 if you have the `flockfile' function. */
+#undef HAVE_FLOCKFILE
+
 /* Build with GeoIP support */
 #undef HAVE_GEOIP
 
@@ -168,6 +171,9 @@
 /* Build with GeoIP Country IPv6 support */
 #undef HAVE_GEOIP_V6
 
+/* Define to 1 if you have the `getc_unlocked' function. */
+#undef HAVE_GETC_UNLOCKED
+
 /* Define to 1 if you have the `getpassphrase' function. */
 #undef HAVE_GETPASSPHRASE
 
diff --git a/configure b/configure
index 851f7203ab..4c97c8c48f 100755
--- a/configure
+++ b/configure
@@ -15246,6 +15246,22 @@ fi
 done
 
 
+#
+# flockfile is usually provided by pthreads
+#
+for ac_func in flockfile getc_unlocked
+do :
+  as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh`
+ac_fn_c_check_func "$LINENO" "$ac_func" "$as_ac_var"
+if eval test \"x\$"$as_ac_var"\" = x"yes"; then :
+  cat >>confdefs.h <<_ACEOF
+#define `$as_echo "HAVE_$ac_func" | $as_tr_cpp` 1
+_ACEOF
+
+fi
+done
+
+
 #
 # Look for sysconf to allow detection of the number of processors.
 #
diff --git a/configure.ac b/configure.ac
index 34af113a3f..d090484f7f 100644
--- a/configure.ac
+++ b/configure.ac
@@ -665,6 +665,11 @@ AC_CHECK_FUNCS([pthread_setaffinity_np cpuset_setaffinity processor_bind sched_s
 AC_CHECK_FUNCS([pthread_setname_np pthread_set_name_np])
 AC_CHECK_HEADERS([pthread_np.h], [], [], [#include <pthread.h>])
 
+#
+# flockfile is usually provided by pthreads
+#
+AC_CHECK_FUNCS([flockfile getc_unlocked])
+
 #
 # Look for sysconf to allow detection of the number of processors.
 #
diff --git a/lib/isc/lex.c b/lib/isc/lex.c
index dce944b6ca..ca5fe6d160 100644
--- a/lib/isc/lex.c
+++ b/lib/isc/lex.c
@@ -433,7 +433,7 @@ isc_lex_gettoken(isc_lex_t *lex, unsigned int options, isc_token_t *tokenp) {
 			if (source->is_file) {
 				stream = source->input;
 
-#if defined(HAVE_FLOCKFILE) && defined(HAVE_GETCUNLOCKED)
+#if defined(HAVE_FLOCKFILE) && defined(HAVE_GETC_UNLOCKED)
 				c = getc_unlocked(stream);
 #else
 				c = getc(stream);