diff --git a/src/com/google/javascript/jscomp/ReplaceToggles.java b/src/com/google/javascript/jscomp/ReplaceToggles.java
index c078c711af0..c1d8fbbb21c 100644
--- a/src/com/google/javascript/jscomp/ReplaceToggles.java
+++ b/src/com/google/javascript/jscomp/ReplaceToggles.java
@@ -41,8 +41,8 @@ class ReplaceToggles implements CompilerPass {
   static final DiagnosticType INVALID_ORDINAL_MAPPING =
       DiagnosticType.error(
           "JSC_INVALID_ORDINAL_MAPPING",
-          "_F_toggleOrdinals must be initialized with an object literal mapping strings to booleans"
-              + " or unique whole numbers: {0}");
+          "CLOSURE_TOGGLE_ORDINALS must be initialized with an object literal mapping strings to"
+              + " booleans or unique whole numbers: {0}");
 
   static final DiagnosticType UNKNOWN_TOGGLE =
       DiagnosticType.error(
@@ -72,7 +72,7 @@ public void process(Node externs, Node root) {
     NodeTraversal.traverse(compiler, root, new Traversal());
   }
 
-  private static final String ORDINAL_VAR_NAME = "_F_toggleOrdinals";
+  private static final String ORDINAL_VAR_NAME = "CLOSURE_TOGGLE_ORDINALS";
   private static final QualifiedName readToggleFunctionName =
       QualifiedName.of("goog.readToggleInternalDoNotCallDirectly");
 
@@ -80,7 +80,7 @@ private class Traversal extends AbstractPostOrderCallback {
 
     @Override
     public void visit(NodeTraversal t, Node n, Node parent) {
-      // Look for `var _F_toggleOrdinals = {...};`.  Note that we only do this in check mode.
+      // Look for `var CLOSURE_TOGGLE_ORDINALS = {...};`.  Note that we only do this in check mode.
       // It's not our responsibility to delete the unused variable in optimized mode - if all
       // the calls to readToggle are deleted, then the bootstrap will be unused and deleted, too.
       if (check
diff --git a/test/com/google/javascript/jscomp/ReplaceTogglesTest.java b/test/com/google/javascript/jscomp/ReplaceTogglesTest.java
index 93de39c1d86..c51a77b8e54 100644
--- a/test/com/google/javascript/jscomp/ReplaceTogglesTest.java
+++ b/test/com/google/javascript/jscomp/ReplaceTogglesTest.java
@@ -42,23 +42,23 @@ public void resetPassParameters() throws Exception {
   @Test
   public void testBootstrapOrdinals_uninitialized() {
     check = true;
-    testSame(srcs("var _F_toggleOrdinals;"), expectOrdinals(null));
+    testSame(srcs("var CLOSURE_TOGGLE_ORDINALS;"), expectOrdinals(null));
   }
 
   @Test
   public void testBootstrapOrdinals_empty() {
     check = true;
-    testSame(srcs("var _F_toggleOrdinals = {};"), expectOrdinals(ImmutableMap.of()));
+    testSame(srcs("var CLOSURE_TOGGLE_ORDINALS = {};"), expectOrdinals(ImmutableMap.of()));
   }
 
   @Test
   public void testBootstrapOrdinals_simple() {
     check = true;
     testSame(
-        srcs("var _F_toggleOrdinals = {'foo_bar': 1};"),
+        srcs("var CLOSURE_TOGGLE_ORDINALS = {'foo_bar': 1};"),
         expectOrdinals(ImmutableMap.of("foo_bar", 1)));
     testSame(
-        srcs("var _F_toggleOrdinals = {'foo_bar': 1, qux: 2};"),
+        srcs("var CLOSURE_TOGGLE_ORDINALS = {'foo_bar': 1, qux: 2};"),
         expectOrdinals(ImmutableMap.of("foo_bar", 1, "qux", 2)));
   }
 
@@ -68,14 +68,14 @@ public void testBootstrapOrdinals_ignoresExtraUninitializedDefinitions() {
     testSame(
         srcs(
             lines(
-                "var _F_toggleOrdinals = {'foo': 1};", //
-                "var _F_toggleOrdinals;")),
+                "var CLOSURE_TOGGLE_ORDINALS = {'foo': 1};", //
+                "var CLOSURE_TOGGLE_ORDINALS;")),
         expectOrdinals(ImmutableMap.of("foo", 1)));
     testSame(
         srcs(
             lines(
-                "var _F_toggleOrdinals;", //
-                "var _F_toggleOrdinals = {'foo': 1};")),
+                "var CLOSURE_TOGGLE_ORDINALS;", //
+                "var CLOSURE_TOGGLE_ORDINALS = {'foo': 1};")),
         expectOrdinals(ImmutableMap.of("foo", 1)));
   }
 
@@ -83,7 +83,7 @@ public void testBootstrapOrdinals_ignoresExtraUninitializedDefinitions() {
   public void testBootstrapOrdinals_booleanAllowed() {
     check = true;
     testSame(
-        srcs("var _F_toggleOrdinals = {'foo_bar': false, 'baz': true};"),
+        srcs("var CLOSURE_TOGGLE_ORDINALS = {'foo_bar': false, 'baz': true};"),
         expectOrdinals(ImmutableMap.of("foo_bar", FALSE_VALUE, "baz", TRUE_VALUE)));
   }
 
@@ -91,10 +91,10 @@ public void testBootstrapOrdinals_booleanAllowed() {
   public void testBootstrapOrdinals_booleanAllowsDuplicates() {
     check = true;
     testSame(
-        srcs("var _F_toggleOrdinals = {'foo_bar': false, 'baz': false, 'qux': 0};"),
+        srcs("var CLOSURE_TOGGLE_ORDINALS = {'foo_bar': false, 'baz': false, 'qux': 0};"),
         expectOrdinals(ImmutableMap.of("foo_bar", FALSE_VALUE, "baz", FALSE_VALUE, "qux", 0)));
     testSame(
-        srcs("var _F_toggleOrdinals = {'foo_bar': true, 'baz': true, 'qux': 0};"),
+        srcs("var CLOSURE_TOGGLE_ORDINALS = {'foo_bar': true, 'baz': true, 'qux': 0};"),
         expectOrdinals(ImmutableMap.of("foo_bar", TRUE_VALUE, "baz", TRUE_VALUE, "qux", 0)));
   }
 
@@ -102,11 +102,11 @@ public void testBootstrapOrdinals_booleanAllowsDuplicates() {
   public void testBootstrapOrdinals_notAnObject() {
     check = true;
     test(
-        srcs("var _F_toggleOrdinals = 1;"),
+        srcs("var CLOSURE_TOGGLE_ORDINALS = 1;"),
         error(ReplaceToggles.INVALID_ORDINAL_MAPPING)
             .withMessageContaining("not an object literal"));
     test(
-        srcs("var _F_toggleOrdinals = [];"),
+        srcs("var CLOSURE_TOGGLE_ORDINALS = [];"),
         error(ReplaceToggles.INVALID_ORDINAL_MAPPING)
             .withMessageContaining("not an object literal"));
   }
@@ -115,13 +115,13 @@ public void testBootstrapOrdinals_notAnObject() {
   public void testBootstrapOrdinals_badKey() {
     check = true;
     test(
-        srcs("var _F_toggleOrdinals = {[x]: 1};"),
+        srcs("var CLOSURE_TOGGLE_ORDINALS = {[x]: 1};"),
         error(ReplaceToggles.INVALID_ORDINAL_MAPPING).withMessageContaining("non-string key"));
     test(
-        srcs("var _F_toggleOrdinals = {['x']: 1};"),
+        srcs("var CLOSURE_TOGGLE_ORDINALS = {['x']: 1};"),
         error(ReplaceToggles.INVALID_ORDINAL_MAPPING).withMessageContaining("non-string key"));
     test(
-        srcs("var _F_toggleOrdinals = {x() { return 1; }};"),
+        srcs("var CLOSURE_TOGGLE_ORDINALS = {x() { return 1; }};"),
         error(ReplaceToggles.INVALID_ORDINAL_MAPPING).withMessageContaining("non-string key"));
   }
 
@@ -129,7 +129,7 @@ public void testBootstrapOrdinals_badKey() {
   public void testBootstrapOrdinals_duplicateKey() {
     check = true;
     test(
-        srcs("var _F_toggleOrdinals = {x: 1, y: 2, x: 3};"),
+        srcs("var CLOSURE_TOGGLE_ORDINALS = {x: 1, y: 2, x: 3};"),
         error(ReplaceToggles.INVALID_ORDINAL_MAPPING).withMessageContaining("duplicate key: x"));
   }
 
@@ -137,35 +137,35 @@ public void testBootstrapOrdinals_duplicateKey() {
   public void testBootstrapOrdinals_badValue() {
     check = true;
     test(
-        srcs("var _F_toggleOrdinals = {x: 'y'};"),
+        srcs("var CLOSURE_TOGGLE_ORDINALS = {x: 'y'};"),
         error(ReplaceToggles.INVALID_ORDINAL_MAPPING)
             .withMessageContaining("value not a boolean or whole number literal"));
     test(
-        srcs("var _F_toggleOrdinals = {x};"),
+        srcs("var CLOSURE_TOGGLE_ORDINALS = {x};"),
         error(ReplaceToggles.INVALID_ORDINAL_MAPPING)
             .withMessageContaining("value not a boolean or whole number literal"));
     test(
-        srcs("var _F_toggleOrdinals = {x: 1 + 2};"),
+        srcs("var CLOSURE_TOGGLE_ORDINALS = {x: 1 + 2};"),
         error(ReplaceToggles.INVALID_ORDINAL_MAPPING)
             .withMessageContaining("value not a boolean or whole number literal"));
     test(
-        srcs("var _F_toggleOrdinals = {x: NaN};"),
+        srcs("var CLOSURE_TOGGLE_ORDINALS = {x: NaN};"),
         error(ReplaceToggles.INVALID_ORDINAL_MAPPING)
             .withMessageContaining("value not a boolean or whole number literal"));
     test(
-        srcs("var _F_toggleOrdinals = {x: Infinity};"),
+        srcs("var CLOSURE_TOGGLE_ORDINALS = {x: Infinity};"),
         error(ReplaceToggles.INVALID_ORDINAL_MAPPING)
             .withMessageContaining("value not a boolean or whole number literal"));
     test(
-        srcs("var _F_toggleOrdinals = {x: -1};"),
+        srcs("var CLOSURE_TOGGLE_ORDINALS = {x: -1};"),
         error(ReplaceToggles.INVALID_ORDINAL_MAPPING)
             .withMessageContaining("value not a boolean or whole number literal"));
     test(
-        srcs("var _F_toggleOrdinals = {x: 1.2};"),
+        srcs("var CLOSURE_TOGGLE_ORDINALS = {x: 1.2};"),
         error(ReplaceToggles.INVALID_ORDINAL_MAPPING)
             .withMessageContaining("value not a boolean or whole number literal"));
     test(
-        srcs("var _F_toggleOrdinals = {x: null};"),
+        srcs("var CLOSURE_TOGGLE_ORDINALS = {x: null};"),
         error(ReplaceToggles.INVALID_ORDINAL_MAPPING)
             .withMessageContaining("value not a boolean or whole number literal"));
   }
@@ -174,7 +174,7 @@ public void testBootstrapOrdinals_badValue() {
   public void testBootstrapOrdinals_duplicateOrdinal() {
     check = true;
     test(
-        srcs("var _F_toggleOrdinals = {x: 1, y: 2, z: 1};"),
+        srcs("var CLOSURE_TOGGLE_ORDINALS = {x: 1, y: 2, z: 1};"),
         error(ReplaceToggles.INVALID_ORDINAL_MAPPING)
             .withMessageContaining("duplicate ordinal: 1"));
   }