diff --git a/tests/core/test_stack_varargs.c b/tests/core/test_stack_varargs.c
index 00f0706787635..0fcf7a5979518 100644
--- a/tests/core/test_stack_varargs.c
+++ b/tests/core/test_stack_varargs.c
@@ -17,7 +17,7 @@ void func(int i) {
       i, i, i, i, i, i, i, i, i, i, i, i, i, i);
 }
 int main() {
-  for (int i = 0; i < 2048; i++) func(i);
+  for (int i = 0; i < 4 * 1024; i++) func(i);
   printf("ok!\n");
   return 0;
 }
diff --git a/tests/test_core.py b/tests/test_core.py
index 239aa57e58205..0fd6bccab1276 100644
--- a/tests/test_core.py
+++ b/tests/test_core.py
@@ -1398,13 +1398,21 @@ def test_stack_byval(self):
     self.do_run_in_out_file_test('tests', 'core', 'test_stack_byval')
 
   def test_stack_varargs(self):
+    # in node.js we allocate argv[0] on the stack, which means the  length
+    # of the program directory influences how much stack we need, and so
+    # long random temp dir names can lead to random failures. The stack
+    # size was increased here to avoid that.
     self.set_setting('INLINING_LIMIT', 50)
-    self.set_setting('TOTAL_STACK', 4096)
+    self.set_setting('TOTAL_STACK', 8 * 1024)
 
     self.do_run_in_out_file_test('tests', 'core', 'test_stack_varargs')
 
   def test_stack_varargs2(self):
-    self.set_setting('TOTAL_STACK', 4096)
+    # in node.js we allocate argv[0] on the stack, which means the  length
+    # of the program directory influences how much stack we need, and so
+    # long random temp dir names can lead to random failures. The stack
+    # size was increased here to avoid that.
+    self.set_setting('TOTAL_STACK', 8 * 1024)
     src = r'''
       #include <stdio.h>
       #include <stdlib.h>
@@ -1412,7 +1420,7 @@ def test_stack_varargs2(self):
       void func(int i) {
       }
       int main() {
-        for (int i = 0; i < 3072; i++) {
+        for (int i = 0; i < 7000; i++) {
           printf("%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d\n",
                    i, i, i, i, i, i, i, i, i, i, i, i, i, i, i, i, i, i, i, i, i, i, i, i, i, i, i, i, i, i, i, i, i, i, i, i, i, i, i);
         }
@@ -1429,7 +1437,7 @@ def test_stack_varargs2(self):
       #include <stdlib.h>
 
       int main() {
-        for (int i = 0; i < 3072; i++) {
+        for (int i = 0; i < 7000; i++) {
           int j = printf("%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d",
                    i, i, i, i, i, i, i, i, i, i, i, i, i, i, i, i, i, i, i, i, i, i, i, i, i, i, i, i, i, i, i, i, i, i, i, i, i, i, i);
           printf(" (%d)\n", j);
@@ -1465,7 +1473,7 @@ def test_stack_varargs2(self):
       }
 
       int main() {
-        for (int i = 0; i < 3072; i++) {
+        for (int i = 0; i < 7000; i++) {
           int j = printf("%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d",
                    i, i, i, i, i, i, i, i, i, i, i, i, i, i, i, i, i, i, i, i, i, i, i, i, i, i, i, i, i, i, i, i, i, i, i, i, i, i, i);
           printf(" (%d)\n", j);