diff --git a/doc/changelog.dox b/doc/changelog.dox
index 2b2b2b921..e1fd41708 100644
--- a/doc/changelog.dox
+++ b/doc/changelog.dox
@@ -945,6 +945,9 @@ See also:
     [mosra/toolchains#13](https://github.com/mosra/toolchains/issues/13),
     [mosra/toolchains#14](https://github.com/mosra/toolchains/pull/14) and
     [mosra/magnum#490](https://github.com/mosra/magnum/issues/490).
+-   @ref Platform::Sdl2Application and @ref Platform::EmscriptenApplication now
+    use `UTF8ToString` instead of `AsciiToString` as the latter is no longer
+    included by default on Emscripten 3.1.21+ (see [mosra/magnum#619](https://github.com/mosra/magnum/issues/619)).
 
 @subsection changelog-latest-bugfixes Bug fixes
 
diff --git a/src/Magnum/Platform/EmscriptenApplication.cpp b/src/Magnum/Platform/EmscriptenApplication.cpp
index 2f6c822f6..4af13d7a9 100644
--- a/src/Magnum/Platform/EmscriptenApplication.cpp
+++ b/src/Magnum/Platform/EmscriptenApplication.cpp
@@ -486,11 +486,7 @@ void EmscriptenApplication::setContainerCssClass(const Containers::StringView cs
     EM_ASM_({
         /* Handle also the classic #container for backwards compatibility. We
            also need to preserve the mn-container otherwise next time we'd have
-           no way to look for it anymore.
-
-           Using UTF8ToString() instead of AsciiToString() as it has an
-           explicit size parameter and thus doesn't need a null-terminated
-           input, which would potentially require yet another allocation. */
+           no way to look for it anymore. */
         (Module['canvas'].closest('.mn-container') ||
          document.getElementById('container')).className = (['mn-container', UTF8ToString($0, $1)]).join(' ');
     }, cssClass.data(), cssClass.size());
@@ -745,7 +741,7 @@ void EmscriptenApplication::setCursor(Cursor cursor) {
     CORRADE_INTERNAL_ASSERT(UnsignedInt(cursor) < Containers::arraySize(CursorMap));
     #pragma GCC diagnostic push
     #pragma GCC diagnostic ignored "-Wdollar-in-identifier-extension"
-    EM_ASM_({Module['canvas'].style.cursor = AsciiToString($0);}, CursorMap[UnsignedInt(cursor)]);
+    EM_ASM_({Module['canvas'].style.cursor = UTF8ToString($0);}, CursorMap[UnsignedInt(cursor)]);
     #pragma GCC diagnostic pop
 }
 
diff --git a/src/Magnum/Platform/Sdl2Application.cpp b/src/Magnum/Platform/Sdl2Application.cpp
index 7407a8b2d..cab1cc188 100644
--- a/src/Magnum/Platform/Sdl2Application.cpp
+++ b/src/Magnum/Platform/Sdl2Application.cpp
@@ -771,11 +771,7 @@ void Sdl2Application::setContainerCssClass(const Containers::StringView cssClass
     EM_ASM_({
         /* Handle also the classic #container for backwards compatibility. We
            also need to preserve the mn-container otherwise next time we'd have
-           no way to look for it anymore.
-
-           Using UTF8ToString() instead of AsciiToString() as it has an
-           explicit size parameter and thus doesn't need a null-terminated
-           input, which would potentially require yet another allocation. */
+           no way to look for it anymore. */
         (Module['canvas'].closest('.mn-container') ||
          document.getElementById('container')).className = (['mn-container', UTF8ToString($0, $1)]).join(' ');
     }, cssClass.data(), cssClass.size());
@@ -1122,7 +1118,7 @@ void Sdl2Application::setCursor(Cursor cursor) {
     CORRADE_INTERNAL_ASSERT(UnsignedInt(cursor) < Containers::arraySize(CursorMap));
     #pragma GCC diagnostic push
     #pragma GCC diagnostic ignored "-Wdollar-in-identifier-extension"
-    EM_ASM_({Module['canvas'].style.cursor = AsciiToString($0);}, CursorMap[UnsignedInt(cursor)]);
+    EM_ASM_({Module['canvas'].style.cursor = UTF8ToString($0);}, CursorMap[UnsignedInt(cursor)]);
     #pragma GCC diagnostic pop
     #endif
 }