diff --git a/src/platform/emscripten/ffi.rs b/src/platform/emscripten/ffi.rs
index 65291a92..f1d12c14 100644
--- a/src/platform/emscripten/ffi.rs
+++ b/src/platform/emscripten/ffi.rs
@@ -3,6 +3,8 @@
 #![allow(non_camel_case_types)]
 
 use std::os::raw::{c_int, c_char, c_void, c_ulong, c_double, c_long, c_ushort};
+#[cfg(test)]
+use std::mem;
 
 pub type EM_BOOL = c_int;
 pub type EM_UTF8 = c_char;
@@ -219,6 +221,15 @@ fn bindgen_test_layout_EmscriptenPointerlockChangeEvent() {
 }
 
 extern "C" {
+    pub fn emscripten_set_canvas_size(
+        width: c_int, height: c_int)
+        -> EMSCRIPTEN_RESULT;
+
+    pub fn emscripten_get_canvas_size(
+        width: *mut c_int, height: *mut c_int,
+        is_fullscreen: *mut c_int)
+        -> EMSCRIPTEN_RESULT;
+
     pub fn emscripten_set_element_css_size(
         target: *const c_char, width: c_double,
         height: c_double) -> EMSCRIPTEN_RESULT;
diff --git a/src/platform/emscripten/mod.rs b/src/platform/emscripten/mod.rs
index 41e9045d..b879bf50 100644
--- a/src/platform/emscripten/mod.rs
+++ b/src/platform/emscripten/mod.rs
@@ -6,7 +6,7 @@ use std::mem;
 use std::os::raw::{c_char, c_void, c_double, c_ulong, c_int};
 use std::ptr;
 use std::sync::atomic::{AtomicBool, Ordering};
-use std::sync::{Mutex, Arc, Weak};
+use std::sync::{Mutex, Arc};
 use std::cell::RefCell;
 use std::collections::VecDeque;
 
@@ -424,10 +424,11 @@ impl Window {
     pub fn get_inner_size(&self) -> Option<(u32, u32)> {
         unsafe {
             use std::{mem, ptr};
-            let mut width = mem::uninitialized();
-            let mut height = mem::uninitialized();
+            let mut width = 0;
+            let mut height = 0;
+            let mut fullscreen = 0;
 
-            if ffi::emscripten_get_element_css_size(ptr::null(), &mut width, &mut height)
+            if ffi::emscripten_get_canvas_size(&mut width, &mut height, &mut fullscreen)
                 != ffi::EMSCRIPTEN_RESULT_SUCCESS
             {
                 None