diff --git a/emcc.py b/emcc.py
index ea63da8f94e71..01a9ef2b0c1fa 100755
--- a/emcc.py
+++ b/emcc.py
@@ -1418,6 +1418,8 @@ def phase_linker_setup(options, state, newargs, settings_map):
     settings.MEMORYPROFILER = 1
 
   if settings.PTHREADS_PROFILING:
+    if not settings.ASSERTIONS:
+      exit_with_error('PTHREADS_PROFILING only works with ASSERTIONS enabled')
     options.post_js.append(utils.path_from_root('src/threadprofiler.js'))
 
   options.pre_js = read_js_files(options.pre_js)
diff --git a/src/library_pthread.js b/src/library_pthread.js
index 038ebd52f577b..f6f2f59008a94 100644
--- a/src/library_pthread.js
+++ b/src/library_pthread.js
@@ -1036,8 +1036,7 @@ var LibraryPThread = {
 #endif
   },
 
-  // The profiler setters are defined twice, here in asm.js so that they can be #if'ed out
-  // without having to pay the impact of a FFI transition for a no-op in non-profiling builds.
+#if ASSERTIONS
   emscripten_conditional_set_current_thread_status__sig: 'vii',
   emscripten_conditional_set_current_thread_status: function(expectedStatus, newStatus) {
 #if PTHREADS_PROFILING
@@ -1058,6 +1057,7 @@ var LibraryPThread = {
     PThread.setThreadName(threadId, UTF8ToString(name));
 #endif
   },
+#endif
 
   // This function is call by a pthread to signal that exit() was called and
   // that the entire process should exit.
diff --git a/system/include/emscripten/threading.h b/system/include/emscripten/threading.h
index f03fd5788f409..4e537cce0ff33 100644
--- a/system/include/emscripten/threading.h
+++ b/system/include/emscripten/threading.h
@@ -312,6 +312,11 @@ void emscripten_thread_sleep(double msecs);
 #define EM_THREAD_STATUS_FINISHED   6
 #define EM_THREAD_STATUS_NUMFIELDS  7
 
+#ifdef NDEBUG
+#define emscripten_set_current_thread_status(newStatus)
+#define emscripten_conditional_set_current_thread_status(expectedStatus, newStatus)
+#define emscripten_set_thread_name(threadId, name)
+#else
 // Sets the profiler status of the calling thread. This is a no-op if thread
 // profiling is not active.
 // This is an internal function and generally not intended for user code.
@@ -332,6 +337,7 @@ void emscripten_conditional_set_current_thread_status(EM_THREAD_STATUS expectedS
 // When thread profiler is not enabled (not building with --threadprofiler),
 // this is a no-op.
 void emscripten_set_thread_name(pthread_t threadId, const char *name);
+#endif
 
 // Gets the stored pointer to a string representing the canvases to transfer to
 // the created thread.
diff --git a/tests/other/metadce/minimal_main_Oz_USE_PTHREADS_PROXY_TO_PTHREAD.exports b/tests/other/metadce/minimal_main_Oz_USE_PTHREADS_PROXY_TO_PTHREAD.exports
index 4460c5af8dd38..7e469e468abf7 100644
--- a/tests/other/metadce/minimal_main_Oz_USE_PTHREADS_PROXY_TO_PTHREAD.exports
+++ b/tests/other/metadce/minimal_main_Oz_USE_PTHREADS_PROXY_TO_PTHREAD.exports
@@ -10,9 +10,9 @@ I
 J
 K
 L
-M
-N
-O
+r
+s
+t
 u
 v
 w
diff --git a/tests/other/metadce/minimal_main_Oz_USE_PTHREADS_PROXY_TO_PTHREAD.imports b/tests/other/metadce/minimal_main_Oz_USE_PTHREADS_PROXY_TO_PTHREAD.imports
index 9479133a56d79..ac4ee2d44f8ad 100644
--- a/tests/other/metadce/minimal_main_Oz_USE_PTHREADS_PROXY_TO_PTHREAD.imports
+++ b/tests/other/metadce/minimal_main_Oz_USE_PTHREADS_PROXY_TO_PTHREAD.imports
@@ -15,6 +15,3 @@ a.n
 a.o
 a.p
 a.q
-a.r
-a.s
-a.t
diff --git a/tests/other/metadce/minimal_main_Oz_USE_PTHREADS_PROXY_TO_PTHREAD.sent b/tests/other/metadce/minimal_main_Oz_USE_PTHREADS_PROXY_TO_PTHREAD.sent
index b64b08c98af4d..f6c3b87f767e8 100644
--- a/tests/other/metadce/minimal_main_Oz_USE_PTHREADS_PROXY_TO_PTHREAD.sent
+++ b/tests/other/metadce/minimal_main_Oz_USE_PTHREADS_PROXY_TO_PTHREAD.sent
@@ -15,6 +15,3 @@ n
 o
 p
 q
-r
-s
-t
diff --git a/tests/other/metadce/minimal_main_Oz_USE_PTHREADS_PROXY_TO_PTHREAD.size b/tests/other/metadce/minimal_main_Oz_USE_PTHREADS_PROXY_TO_PTHREAD.size
index 424790743c383..d10e00f1b1a56 100644
--- a/tests/other/metadce/minimal_main_Oz_USE_PTHREADS_PROXY_TO_PTHREAD.size
+++ b/tests/other/metadce/minimal_main_Oz_USE_PTHREADS_PROXY_TO_PTHREAD.size
@@ -1 +1 @@
-16909
+16826