diff --git a/dom/plugins/test/mochitest/test_GCrace.html b/dom/plugins/test/mochitest/test_GCrace.html
index 45346f5c481..a18d297cb09 100644
--- a/dom/plugins/test/mochitest/test_GCrace.html
+++ b/dom/plugins/test/mochitest/test_GCrace.html
@@ -21,7 +21,7 @@
       }
       else {
         if (navigator.platform.startsWith("Win")) {
-          SimpleTest.expectAssertions(0, 250);
+          SimpleTest.expectAssertions(0, 350);
         } else {
           SimpleTest.expectAssertions(0, 1);
         }
diff --git a/layout/generic/test/test_selection_preventDefault.html b/layout/generic/test/test_selection_preventDefault.html
index 124f8144cd8..7f8debdedb6 100644
--- a/layout/generic/test/test_selection_preventDefault.html
+++ b/layout/generic/test/test_selection_preventDefault.html
@@ -33,7 +33,7 @@ dddddd dddddd dddddd
 <script class="testbody" type="text/javascript">
 
 if (navigator.platform.startsWith("Win")) {
-  SimpleTest.expectAssertions(0, 1);
+  SimpleTest.expectAssertions(0, 2);
 }
 
 var fixedDiv1 = document.getElementById("fixedDiv1");
diff --git a/toolkit/content/tests/chrome/test_bug509732.xul b/toolkit/content/tests/chrome/test_bug509732.xul
index 70b1879fcff..2ede74567e4 100644
--- a/toolkit/content/tests/chrome/test_bug509732.xul
+++ b/toolkit/content/tests/chrome/test_bug509732.xul
@@ -17,7 +17,7 @@
   <!-- test code goes here -->
 <script type="application/javascript">
 <![CDATA[
-if (navigator.platform.startsWith("Mac")) {
+if (!navigator.platform.startsWith("Linux")) {
   SimpleTest.expectAssertions(0, 7);
 }
 
diff --git a/toolkit/content/tests/chrome/test_button.xul b/toolkit/content/tests/chrome/test_button.xul
index b67c1d04ba7..8f7ec0a1ca4 100644
--- a/toolkit/content/tests/chrome/test_button.xul
+++ b/toolkit/content/tests/chrome/test_button.xul
@@ -28,11 +28,7 @@
 <script type="application/javascript">
 <![CDATA[
 
-if (navigator.platform.startsWith("Mac")) {
-  SimpleTest.expectAssertions(0, 7);
-} else {
-  SimpleTest.expectAssertions(0, 5);
-}
+SimpleTest.expectAssertions(0, 7);
 
 SimpleTest.waitForExplicitFinish();
 
diff --git a/toolkit/content/tests/chrome/test_largemenu.xul b/toolkit/content/tests/chrome/test_largemenu.xul
index bb6585259a7..284b163e614 100644
--- a/toolkit/content/tests/chrome/test_largemenu.xul
+++ b/toolkit/content/tests/chrome/test_largemenu.xul
@@ -13,7 +13,7 @@
 
 <script>
 if (!navigator.platform.startsWith("Win")) {
-  SimpleTest.expectAssertions(0, 3);
+  SimpleTest.expectAssertions(0, 4);
 }
 
 SimpleTest.waitForExplicitFinish();