diff --git a/include/cyclone/runtime.h b/include/cyclone/runtime.h
index 7a2aa7a4..91e3927d 100644
--- a/include/cyclone/runtime.h
+++ b/include/cyclone/runtime.h
@@ -229,7 +229,7 @@ extern const object primitive_Cyc_91cvar_127;
 extern const object primitive_Cyc_91has_91cycle_127;
 extern const object primitive_Cyc_91spawn_91thread_67;
 extern const object primitive_Cyc_91end_91thread_67;
-extern const object primitive_Cyc_91thread_91sleep_67;
+extern const object primitive_thread_91sleep_67;
 extern const object primitive__87;
 extern const object primitive__91;
 extern const object primitive__85;
diff --git a/runtime.c b/runtime.c
index 77a4132d..0606400a 100644
--- a/runtime.c
+++ b/runtime.c
@@ -1709,8 +1709,8 @@ void _Cyc_91spawn_91thread_67(void *data, object cont, object args) {
 void _Cyc_91end_91thread_67(void *data, object cont, object args) {
     Cyc_end_thread((gc_thread_data *)data);
     return_closcall1(data, cont, boolean_f); }
-void _Cyc_91thread_91sleep_67(void *data, object cont, object args) {
-    Cyc_check_num_args(data, "Cyc-thread-sleep!", 1, args);
+void _thread_91sleep_67(void *data, object cont, object args) {
+    Cyc_check_num_args(data, "thread-sleep!", 1, args);
     return_closcall1(data, cont, Cyc_thread_sleep(data, car(args))); }
 void __87(void *data, object cont, object args) {
     integer_type argc = Cyc_length(data, args);
@@ -2903,7 +2903,7 @@ static primitive_type Cyc_91cvar_127_primitive = {{0}, primitive_tag, "Cyc-cvar?
 static primitive_type Cyc_91has_91cycle_127_primitive = {{0}, primitive_tag, "Cyc-has-cycle?", &_Cyc_91has_91cycle_127};
 static primitive_type Cyc_91spawn_91thread_67_primitive = {{0}, primitive_tag, "Cyc-spawn-thread!", &_Cyc_91spawn_91thread_67};
 static primitive_type Cyc_91end_91thread_67_primitive = {{0}, primitive_tag, "Cyc-end-thread!", &_Cyc_91end_91thread_67};
-static primitive_type Cyc_91thread_91sleep_67_primitive = {{0}, primitive_tag, "Cyc-thread-sleep!", &_Cyc_91thread_91sleep_67};
+static primitive_type thread_91sleep_67_primitive = {{0}, primitive_tag, "thread-sleep!", &_thread_91sleep_67};
 static primitive_type _87_primitive = {{0}, primitive_tag, "+", &__87};
 static primitive_type _91_primitive = {{0}, primitive_tag, "-", &__91};
 static primitive_type _85_primitive = {{0}, primitive_tag, "*", &__85};
@@ -3023,7 +3023,7 @@ const object primitive_Cyc_91cvar_127 = &Cyc_91cvar_127_primitive;
 const object primitive_Cyc_91has_91cycle_127 = &Cyc_91has_91cycle_127_primitive;
 const object primitive_Cyc_91spawn_91thread_67 = &Cyc_91spawn_91thread_67_primitive;
 const object primitive_Cyc_91end_91thread_67 = &Cyc_91end_91thread_67_primitive;
-const object primitive_Cyc_91thread_91sleep_67 = &Cyc_91thread_91sleep_67_primitive;
+const object primitive_thread_91sleep_67 = &thread_91sleep_67_primitive;
 const object primitive__87 = &_87_primitive;
 const object primitive__91 = &_91_primitive;
 const object primitive__85 = &_85_primitive;
@@ -3211,6 +3211,7 @@ void Cyc_end_thread(gc_thread_data *thd)
 // For now, accept a number of milliseconds to sleep
 object Cyc_thread_sleep(void *data, object timeout)
 {
+  // TODO: looks like there are overflow issues here:
   struct timespec tim;
   Cyc_check_num(data, timeout);
   tim.tv_sec = 0;
diff --git a/scheme/cyclone/cgen.sld b/scheme/cyclone/cgen.sld
index a2e2e58e..f6cdc891 100644
--- a/scheme/cyclone/cgen.sld
+++ b/scheme/cyclone/cgen.sld
@@ -452,7 +452,7 @@
      ((eq? p 'Cyc-has-cycle?)        "Cyc_has_cycle")
      ((eq? p 'Cyc-spawn-thread!)     "Cyc_spawn_thread")
      ((eq? p 'Cyc-end-thread!)       "Cyc_end_thread")
-     ((eq? p 'Cyc-thread-sleep!)     "Cyc_thread_sleep")
+     ((eq? p 'thread-sleep!)         "Cyc_thread_sleep")
      ((eq? p 'Cyc-stdout)            "Cyc_stdout")
      ((eq? p 'Cyc-stdin)             "Cyc_stdin")
      ((eq? p 'Cyc-stderr)            "Cyc_stderr")
@@ -584,7 +584,7 @@
     apply
     Cyc-default-exception-handler
     Cyc-end-thread!
-    Cyc-thread-sleep!
+    thread-sleep!
     open-input-file
     open-output-file
     close-port
diff --git a/scheme/cyclone/transforms.sld b/scheme/cyclone/transforms.sld
index 9d115abb..290630e3 100644
--- a/scheme/cyclone/transforms.sld
+++ b/scheme/cyclone/transforms.sld
@@ -453,7 +453,7 @@
      Cyc-has-cycle?
      Cyc-spawn-thread!
      Cyc-end-thread!
-     Cyc-thread-sleep!
+     thread-sleep!
      Cyc-stdout
      Cyc-stdin
      Cyc-stderr
@@ -559,7 +559,7 @@
                   Cyc-cvar?
                   Cyc-spawn-thread!
                   Cyc-end-thread!
-                  Cyc-thread-sleep!
+                  thread-sleep!
                   apply
                   %halt
                   exit
diff --git a/scheme/eval.sld b/scheme/eval.sld
index 1cabf452..2171b490 100644
--- a/scheme/eval.sld
+++ b/scheme/eval.sld
@@ -138,7 +138,7 @@
       (list 'Cyc-has-cycle? Cyc-has-cycle?)
       (list 'Cyc-spawn-thread! Cyc-spawn-thread!)
       (list 'Cyc-end-thread! Cyc-end-thread!)
-      (list 'Cyc-thread-sleep! Cyc-thread-sleep!)
+      (list 'thread-sleep! thread-sleep!)
       (list 'Cyc-default-exception-handler Cyc-default-exception-handler)
       (list 'Cyc-current-exception-handler Cyc-current-exception-handler)
       (list '+ +)