diff --git a/configure.ac b/configure.ac
index 92f40c17ac..a27b22543c 100644
--- a/configure.ac
+++ b/configure.ac
@@ -171,7 +171,7 @@ AC_ARG_ENABLE([developer],
 
 AS_IF([test "$enable_developer" = "yes"],
       [DEVELOPER_MODE=yes
-       STD_CPPFLAGS="$STD_CPPFLAGS -DISC_MEM_DEFAULTFILL=1 -DISC_MEM_TRACKLINES=1 -DISC_LIST_CHECKINIT=1 -DISC_STATS_CHECKUNDERFLOW=1 -DDNS_RBTDB_STRONG_RWLOCK_CHECK=1"
+       STD_CPPFLAGS="$STD_CPPFLAGS -DISC_MEM_DEFAULTFILL=1 -DISC_MEM_TRACKLINES=1 -DISC_LIST_CHECKINIT=1 -DISC_STATS_CHECKUNDERFLOW=1 -DDNS_RBTDB_STRONG_RWLOCK_CHECK=1 -DISC_MUTEX_ERROR_CHECK=1"
        test "${enable_fixed_rrset+set}" = set || enable_fixed_rrset=yes
        test "${enable_querytrace+set}" = set || enable_querytrace=yes
        test "${with_cmocka+set}" = set || with_cmocka=yes
@@ -562,30 +562,6 @@ AC_ARG_WITH([locktype],
 			    (adaptive or standard)]),
 	    [], [with_locktype="adaptive"])
 
-AS_CASE([$with_locktype],
-	[adaptive],[
-	  AC_MSG_CHECKING([for PTHREAD_MUTEX_ADAPTIVE_NP])
-	  AC_COMPILE_IFELSE(
-	    [AC_LANG_PROGRAM(
-	       [[
-		 #ifndef _GNU_SOURCE
-		 #define _GNU_SOURCE
-		 #endif
-		 #include <pthread.h>
-	       ]],
-	       [[
-		 return (PTHREAD_MUTEX_ADAPTIVE_NP);
-	       ]]
-	     )],
-	    [AC_MSG_RESULT([using adaptive lock type])
-	     AC_DEFINE([HAVE_PTHREAD_MUTEX_ADAPTIVE_NP], 1,
-		       [Support for PTHREAD_MUTEX_ADAPTIVE_NP]) ],
-	    [AC_MSG_RESULT([using standard lock type])]
-	  )],
-	[standard],[AC_MSG_RESULT([using standard lock type])],
-	[AC_MSG_ERROR([You must specify "adaptive" or "standard" for --with-locktype.])]
-       )
-
 AC_CHECK_HEADERS([sched.h])
 
 AC_SEARCH_LIBS([sched_yield],[rt])
diff --git a/lib/isc/include/isc/mutex.h b/lib/isc/include/isc/mutex.h
index 45256a6fac..341148a753 100644
--- a/lib/isc/include/isc/mutex.h
+++ b/lib/isc/include/isc/mutex.h
@@ -23,7 +23,13 @@
 #include <isc/result.h> /* for ISC_R_ codes */
 #include <isc/util.h>
 
+#if ISC_MUTEX_ERROR_CHECK && defined(PTHREAD_ERRORCHECK_MUTEX_INITIALIZER_NP)
+#define ISC_MUTEX_INITIALIZER PTHREAD_ERRORCHECK_MUTEX_INITIALIZER_NP
+#elif defined(PTHREAD_ADAPTIVE_MUTEX_INITIALIZER_NP)
+#define ISC_MUTEX_INITIALIZER PTHREAD_ADAPTIVE_MUTEX_INITIALIZER_NP
+#else
 #define ISC_MUTEX_INITIALIZER PTHREAD_MUTEX_INITIALIZER
+#endif
 
 ISC_LANG_BEGINDECLS
 
diff --git a/lib/isc/mutex.c b/lib/isc/mutex.c
index e591ffe872..67815eb7e9 100644
--- a/lib/isc/mutex.c
+++ b/lib/isc/mutex.c
@@ -33,7 +33,11 @@ static isc_once_t init_once = ISC_ONCE_INIT;
 static void
 mutex_initialize(void) {
 	RUNTIME_CHECK(pthread_mutexattr_init(&isc__mutex_init_attr) == 0);
-#ifdef HAVE_PTHREAD_MUTEX_ADAPTIVE_NP
+#if ISC_MUTEX_ERROR_CHECK && defined(PTHREAD_MUTEX_ERRORCHECK_NP)
+	RUNTIME_CHECK(pthread_mutexattr_settype(&isc__mutex_init_attr,
+						PTHREAD_MUTEX_ERRORCHECK_NP) ==
+		      0);
+#elif defined(PTHREAD_MUTEX_ADAPTIVE_NP)
 	RUNTIME_CHECK(pthread_mutexattr_settype(&isc__mutex_init_attr,
 						PTHREAD_MUTEX_ADAPTIVE_NP) ==
 		      0);
diff --git a/lib/isc/netmgr/netmgr-int.h b/lib/isc/netmgr/netmgr-int.h
index 9363119d3e..596333d1dd 100644
--- a/lib/isc/netmgr/netmgr-int.h
+++ b/lib/isc/netmgr/netmgr-int.h
@@ -328,7 +328,6 @@ struct isc_nm {
 	isc_mem_t *mctx;
 	isc_loopmgr_t *loopmgr;
 	uint32_t nloops;
-	isc_mutex_t lock;
 	isc__networker_t *workers;
 
 	isc_stats_t *stats;
diff --git a/lib/isc/netmgr/netmgr.c b/lib/isc/netmgr/netmgr.c
index ea1c561a62..6cbc8a4bf2 100644
--- a/lib/isc/netmgr/netmgr.c
+++ b/lib/isc/netmgr/netmgr.c
@@ -179,7 +179,6 @@ isc_netmgr_create(isc_mem_t *mctx, isc_loopmgr_t *loopmgr, isc_nm_t **netmgrp) {
 	};
 
 	isc_mem_attach(mctx, &netmgr->mctx);
-	isc_mutex_init(&netmgr->lock);
 	isc_refcount_init(&netmgr->references, 1);
 	atomic_init(&netmgr->maxudp, 0);
 	atomic_init(&netmgr->shuttingdown, false);
@@ -253,8 +252,6 @@ nm_destroy(isc_nm_t **mgr0) {
 		isc_stats_detach(&mgr->stats);
 	}
 
-	isc_mutex_destroy(&mgr->lock);
-
 	isc_mem_cput(mgr->mctx, mgr->workers, mgr->nloops,
 		     sizeof(mgr->workers[0]));
 	isc_mem_putanddetach(&mgr->mctx, mgr, sizeof(*mgr));