diff --git a/system/lib/emmalloc.c b/system/lib/emmalloc.c
index 1fcad3318f363..8d144f616a7af 100644
--- a/system/lib/emmalloc.c
+++ b/system/lib/emmalloc.c
@@ -107,7 +107,7 @@ typedef struct RootRegion
   uint8_t* endPtr;
 } RootRegion;
 
-#if defined(__EMSCRIPTEN_PTHREADS__)
+#ifdef __EMSCRIPTEN_SHARED_MEMORY__
 // In multithreaded builds, use a simple global spinlock strategy to acquire/release access to the memory allocator.
 static volatile uint8_t multithreadingLock = 0;
 #define MALLOC_ACQUIRE() while(__sync_lock_test_and_set(&multithreadingLock, 1)) { while(multithreadingLock) { /*nop*/ } }
diff --git a/system/lib/sbrk.c b/system/lib/sbrk.c
index e443ddf3ba893..21f2d570956eb 100644
--- a/system/lib/sbrk.c
+++ b/system/lib/sbrk.c
@@ -12,7 +12,7 @@
 #include <limits.h>
 #include <stddef.h>
 #include <stdint.h>
-#if __EMSCRIPTEN_PTHREADS__ // for error handling, see below
+#ifdef __EMSCRIPTEN_SHARED_MEMORY__ // for error handling, see below
 #include <stdio.h>
 #include <stdlib.h>
 #endif
@@ -54,16 +54,16 @@ void *sbrk(intptr_t increment_) {
   uintptr_t old_size;
   uintptr_t increment = (uintptr_t)increment_;
   increment = (increment + (SBRK_ALIGNMENT-1)) & ~(SBRK_ALIGNMENT-1);
-#if __EMSCRIPTEN_PTHREADS__
+#ifdef __EMSCRIPTEN_SHARED_MEMORY__
   // Our default dlmalloc uses locks around each malloc/free, so no additional
   // work is necessary to keep things threadsafe, but we also make sure sbrk
   // itself is threadsafe so alternative allocators work. We do that by looping
   // and retrying if we hit interference with another thread.
   uintptr_t expected;
   while (1) {
-#endif // __EMSCRIPTEN_PTHREADS__
+#endif // __EMSCRIPTEN_SHARED_MEMORY__
     uintptr_t* sbrk_ptr = emscripten_get_sbrk_ptr();
-#if __EMSCRIPTEN_PTHREADS__
+#ifdef __EMSCRIPTEN_SHARED_MEMORY__
     uintptr_t old_brk = __c11_atomic_load((_Atomic(uintptr_t)*)sbrk_ptr, __ATOMIC_SEQ_CST);
 #else
     uintptr_t old_brk = *sbrk_ptr;
@@ -81,7 +81,7 @@ void *sbrk(intptr_t increment_) {
         goto Error;
       }
     }
-#if __EMSCRIPTEN_PTHREADS__
+#ifdef __EMSCRIPTEN_SHARED_MEMORY__
     // Attempt to update the dynamic top to new value. Another thread may have
     // beat this one to the update, in which case we will need to start over
     // by iterating the loop body again.
@@ -93,18 +93,18 @@ void *sbrk(intptr_t increment_) {
     if (expected != old_brk) {
       continue;
     }
-#else // __EMSCRIPTEN_PTHREADS__
+#else // __EMSCRIPTEN_SHARED_MEMORY__
     *sbrk_ptr = new_brk;
-#endif // __EMSCRIPTEN_PTHREADS__
+#endif // __EMSCRIPTEN_SHARED_MEMORY__
 
 #ifdef __EMSCRIPTEN_TRACING__
     emscripten_memprof_sbrk_grow(old_brk, new_brk);
 #endif
     return (void*)old_brk;
 
-#if __EMSCRIPTEN_PTHREADS__
+#ifdef __EMSCRIPTEN_SHARED_MEMORY__
   }
-#endif // __EMSCRIPTEN_PTHREADS__
+#endif // __EMSCRIPTEN_SHARED_MEMORY__
 
 Error:
   SET_ERRNO();
@@ -112,7 +112,7 @@ void *sbrk(intptr_t increment_) {
 }
 
 int brk(void* ptr) {
-#if __EMSCRIPTEN_PTHREADS__
+#ifdef __EMSCRIPTEN_SHARED_MEMORY__
   // FIXME
   printf("brk() is not theadsafe yet, https://github.com/emscripten-core/emscripten/issues/10006");
   abort();
diff --git a/test/code_size/hello_wasm_worker_wasm.json b/test/code_size/hello_wasm_worker_wasm.json
index e3837cd951cb2..13b3212340a7d 100644
--- a/test/code_size/hello_wasm_worker_wasm.json
+++ b/test/code_size/hello_wasm_worker_wasm.json
@@ -3,8 +3,8 @@
   "a.html.gz": 433,
   "a.js": 733,
   "a.js.gz": 463,
-  "a.wasm": 1805,
-  "a.wasm.gz": 1002,
+  "a.wasm": 1861,
+  "a.wasm.gz": 1031,
   "total": 3275,
   "total_gz": 1898
 }