diff --git a/lib/isc/pthreads/include/isc/thread.h b/lib/isc/pthreads/include/isc/thread.h
index 66c6e1c439..037a44cf5b 100644
--- a/lib/isc/pthreads/include/isc/thread.h
+++ b/lib/isc/pthreads/include/isc/thread.h
@@ -52,6 +52,6 @@ isc_thread_setname(isc_thread_t thread, const char *name);
 isc_result_t
 isc_thread_setaffinity(int cpu);
 
-#define isc_thread_self (unsigned long)pthread_self
+#define isc_thread_self (uintptr_t) pthread_self
 
 ISC_LANG_ENDDECLS
diff --git a/lib/isc/rwlock.c b/lib/isc/rwlock.c
index f21b4d0526..3441ce5c14 100644
--- a/lib/isc/rwlock.c
+++ b/lib/isc/rwlock.c
@@ -175,7 +175,7 @@ isc__rwlock_lock(isc_rwlock_t *rwl, isc_rwlocktype_t type);
 static void
 print_lock(const char *operation, isc_rwlock_t *rwl, isc_rwlocktype_t type) {
 	fprintf(stderr,
-		"rwlock %p thread %lu %s(%s): "
+		"rwlock %p thread %" PRIuPTR " %s(%s): "
 		"write_requests=%u, write_completions=%u, "
 		"cnt_and_flag=0x%x, readers_waiting=%u, "
 		"write_granted=%u, write_quota=%u\n",
diff --git a/lib/isc/task.c b/lib/isc/task.c
index da0f4d90e5..a618d5b65b 100644
--- a/lib/isc/task.c
+++ b/lib/isc/task.c
@@ -61,13 +61,14 @@
  */
 
 #ifdef ISC_TASK_TRACE
-#define XTRACE(m)                                                            \
-	fprintf(stderr, "task %p thread %lu: %s\n", task, isc_thread_self(), \
-		(m))
-#define XTTRACE(t, m) \
-	fprintf(stderr, "task %p thread %lu: %s\n", (t), isc_thread_self(), (m))
+#define XTRACE(m)                                                  \
+	fprintf(stderr, "task %p thread %" PRIuPTR ": %s\n", task, \
+		isc_thread_self(), (m))
+#define XTTRACE(t, m)                                             \
+	fprintf(stderr, "task %p thread %" PRIuPTR ": %s\n", (t), \
+		isc_thread_self(), (m))
 #define XTHREADTRACE(m) \
-	fprintf(stderr, "thread %lu: %s\n", isc_thread_self(), (m))
+	fprintf(stderr, "thread %" PRIuPTR ": %s\n", isc_thread_self(), (m))
 #else /* ifdef ISC_TASK_TRACE */
 #define XTRACE(m)
 #define XTTRACE(t, m)
diff --git a/lib/isc/trampoline.c b/lib/isc/trampoline.c
index c8ce5a4cad..009e8d136b 100644
--- a/lib/isc/trampoline.c
+++ b/lib/isc/trampoline.c
@@ -26,7 +26,7 @@
 
 struct isc__trampoline {
 	int tid; /* const */
-	isc_thread_t self;
+	uintptr_t self;
 	isc_threadfunc_t start;
 	isc_threadarg_t arg;
 };
diff --git a/lib/isc/win32/condition.c b/lib/isc/win32/condition.c
index 0f835f97cf..0859ff6fbb 100644
--- a/lib/isc/win32/condition.c
+++ b/lib/isc/win32/condition.c
@@ -93,7 +93,7 @@ register_thread(unsigned long thrd, isc_condition_t *gblcond,
 }
 
 static isc_result_t
-find_thread_condition(unsigned long thrd, isc_condition_t *cond,
+find_thread_condition(uintptr_t thrd, isc_condition_t *cond,
 		      isc_condition_thread_t **threadcondp) {
 	isc_condition_thread_t *threadcond;
 
diff --git a/lib/isc/win32/include/isc/condition.h b/lib/isc/win32/include/isc/condition.h
index 39a1420b18..fc4e96c8f3 100644
--- a/lib/isc/win32/include/isc/condition.h
+++ b/lib/isc/win32/include/isc/condition.h
@@ -22,8 +22,8 @@
 typedef struct isc_condition_thread isc_condition_thread_t;
 
 struct isc_condition_thread {
-	unsigned long th;
-	HANDLE	      handle[2];
+	uintptr_t th;
+	HANDLE	  handle[2];
 	ISC_LINK(isc_condition_thread_t) link;
 };
 
diff --git a/lib/isc/win32/include/isc/thread.h b/lib/isc/win32/include/isc/thread.h
index 49776b8daa..1927bda4de 100644
--- a/lib/isc/win32/include/isc/thread.h
+++ b/lib/isc/win32/include/isc/thread.h
@@ -12,6 +12,7 @@
 #ifndef ISC_THREAD_H
 #define ISC_THREAD_H 1
 
+#include <inttypes.h>
 #include <windows.h>
 
 #include <isc/lang.h>
@@ -68,7 +69,7 @@ typedef DWORD  isc_threadresult_t;
 typedef void * isc_threadarg_t;
 typedef isc_threadresult_t(WINAPI *isc_threadfunc_t)(isc_threadarg_t);
 
-#define isc_thread_self (unsigned long)GetCurrentThreadId
+#define isc_thread_self (uintptr_t) GetCurrentThreadId
 
 ISC_LANG_BEGINDECLS
 
diff --git a/lib/ns/query.c b/lib/ns/query.c
index 52e40922c9..96150d29a8 100644
--- a/lib/ns/query.c
+++ b/lib/ns/query.c
@@ -161,18 +161,17 @@ client_trace(ns_client_t *client, int level, const char *message) {
 					     sizeof(tbuf));
 			isc_log_write(ns_lctx, NS_LOGCATEGORY_CLIENT,
 				      NS_LOGMODULE_QUERY, level,
-				      "query client=%p thread=0x%lx "
+				      "query client=%p thread=0x%" PRIxPTR
 				      "(%s/%s): %s",
-				      client, (unsigned long)isc_thread_self(),
-				      qbuf, tbuf, message);
+				      client, isc_thread_self(), qbuf, tbuf,
+				      message);
 		}
 	} else {
 		isc_log_write(ns_lctx, NS_LOGCATEGORY_CLIENT,
 			      NS_LOGMODULE_QUERY, level,
-			      "query client=%p thread=0x%lx "
+			      "query client=%p thread=0x%" PRIxPTR
 			      "(<unknown-query>): %s",
-			      client, (unsigned long)isc_thread_self(),
-			      message);
+			      client, isc_thread_self(), message);
 	}
 }
 #define CTRACE(l, m)  client_trace(client, l, m)