diff --git a/src/stackwalk.c b/src/stackwalk.c
index bb15ebe754533..d4f6aeecad51e 100644
--- a/src/stackwalk.c
+++ b/src/stackwalk.c
@@ -1158,12 +1158,18 @@ JL_DLLEXPORT void jl_print_backtrace(void) JL_NOTSAFEPOINT
     jlbacktrace();
 }
 
+extern int gc_first_tid;
+
 // Print backtraces for all live tasks, for all threads, to jl_safe_printf stderr
 JL_DLLEXPORT void jl_print_task_backtraces(int show_done) JL_NOTSAFEPOINT
 {
     size_t nthreads = jl_atomic_load_acquire(&jl_n_threads);
     jl_ptls_t *allstates = jl_atomic_load_relaxed(&jl_all_tls_states);
     for (size_t i = 0; i < nthreads; i++) {
+        // skip GC threads since they don't have tasks
+        if (gc_first_tid <= i && i < gc_first_tid + jl_n_gcthreads) {
+            continue;
+        }
         jl_ptls_t ptls2 = allstates[i];
         if (ptls2 == NULL) {
             continue;
diff --git a/uv_constants.jl b/uv_constants.jl
new file mode 100644
index 0000000000000..1db24e45bc2fc
--- /dev/null
+++ b/uv_constants.jl
@@ -0,0 +1,5 @@
+-mmacosx-version-min=11.0
+
+-P
+-I/Users/dnetto/RAI/julia-RAI/usr/include
+16