diff --git a/frontend_tests/node_tests/emoji.js b/frontend_tests/node_tests/emoji.js
index ce83a1c82e..ccfcc3db9a 100644
--- a/frontend_tests/node_tests/emoji.js
+++ b/frontend_tests/node_tests/emoji.js
@@ -45,7 +45,7 @@ run_test('initialize', () => {
     emoji.initialize();
     assert(image_stub);
     assert.equal(calls, 2);
-    assert.deepEqual(urls, ['/static/generated/emoji/sheet_google_64.png',
+    assert.deepEqual(urls, ['/static/generated/emoji/sheet-google-64.png',
                             '/static/generated/emoji/images-google-64/1f419.png']);
 
     // Check initialization sequence for `text` emojiset.
@@ -56,7 +56,7 @@ run_test('initialize', () => {
     emoji.initialize();
     assert(image_stub);
     assert.equal(calls, 2);
-    assert.deepEqual(urls, ['/static/generated/emoji/sheet_google_64.png',
+    assert.deepEqual(urls, ['/static/generated/emoji/sheet-google-64.png',
                             '/static/generated/emoji/images-google-64/1f419.png']);
 });
 
diff --git a/static/js/emoji.js b/static/js/emoji.js
index a76d553949..d970dbc65a 100644
--- a/static/js/emoji.js
+++ b/static/js/emoji.js
@@ -96,7 +96,7 @@ exports.initialize = function initialize() {
     // Load the sprite image and octopus image in the background, so
     // that the browser will cache it for later use.
     var sprite = new Image();
-    sprite.src = '/static/generated/emoji/sheet_' + emojiset + '_64.png';
+    sprite.src = '/static/generated/emoji/sheet-' + emojiset + '-64.png';
     var octopus_image = new Image();
     octopus_image.src = '/static/generated/emoji/images-' + emojiset + '-64/1f419.png';
 };
diff --git a/static/js/settings_display.js b/static/js/settings_display.js
index 842f15388d..64efd74caa 100644
--- a/static/js/settings_display.js
+++ b/static/js/settings_display.js
@@ -146,7 +146,7 @@ exports.report_emojiset_change = function () {
         var sprite_css_href = "/static/generated/emoji/" + page_params.emojiset + "_sprite.css";
         $("#emoji-spritesheet").attr('href', sprite_css_href);
     };
-    sprite.src = "/static/generated/emoji/sheet_" + page_params.emojiset + "_64.png";
+    sprite.src = "/static/generated/emoji/sheet-" + page_params.emojiset + "-64.png";
 };
 
 exports.update_page = function () {
diff --git a/tools/setup/emoji/build_emoji b/tools/setup/emoji/build_emoji
index 729cd01439..387ebfa84a 100755
--- a/tools/setup/emoji/build_emoji
+++ b/tools/setup/emoji/build_emoji
@@ -50,7 +50,7 @@ div.emoji,
 span.emoji
 {
     display: inline-block;
-    background-image: url('sheet_%(emojiset)s_64.png');
+    background-image: url('sheet-%(emojiset)s-64.png');
     -webkit-background-size: 5200%%;
     -moz-background-size: 5200%%;
     background-size: 5200%%;
@@ -163,7 +163,7 @@ def setup_emoji_farms(cache_path: str, emoji_data: List[Dict[str, Any]]) -> None
         # Copy spritesheets.
         emoji_data_path = os.path.join(NODE_MODULES_PATH, 'emoji-datasource-' + emojiset)
         input_sprite_sheet = os.path.join(emoji_data_path, 'img', emojiset, 'sheets-256', '64.png')
-        output_sprite_sheet = os.path.join(cache_path, 'sheet_%s_64.png' % (emojiset,))
+        output_sprite_sheet = os.path.join(cache_path, 'sheet-%s-64.png' % (emojiset,))
         run(['cp', input_sprite_sheet, output_sprite_sheet])
 
         # We hardcode octopus emoji image to Google emojiset's old
diff --git a/tools/setup/emoji/generate_emoji_names_table b/tools/setup/emoji/generate_emoji_names_table
index 32a5931089..26fa9b1d80 100755
--- a/tools/setup/emoji/generate_emoji_names_table
+++ b/tools/setup/emoji/generate_emoji_names_table
@@ -99,19 +99,19 @@ TABLE_CSS = """
     }
 
     .google {
-        background-image: url('sheet_google_64.png') !important;
+        background-image: url('sheet-google-64.png') !important;
     }
 
     .apple {
-        background-image: url('sheet_apple_64.png') !important;
+        background-image: url('sheet-apple-64.png') !important;
     }
 
     .emojione {
-        background-image: url('sheet_emojione_64.png') !important;
+        background-image: url('sheet-emojione-64.png') !important;
     }
 
     .twitter {
-        background-image: url('sheet_twitter_64.png') !important;
+        background-image: url('sheet-twitter-64.png') !important;
     }
 """