diff --git a/src/library.js b/src/library.js
index 20a5ed468ea4..a33161c9ead0 100644
--- a/src/library.js
+++ b/src/library.js
@@ -186,7 +186,7 @@ addToLibrary({
   // it. Returns 1 on success, 0 on error.
   $growMemory: (size) => {
     var b = wasmMemory.buffer;
-    var pages = (size - b.byteLength + {{{ WASM_PAGE_SIZE - 1 }}}) / {{{ WASM_PAGE_SIZE }}};
+    var pages = ((size - b.byteLength + {{{ WASM_PAGE_SIZE - 1 }}}) / {{{ WASM_PAGE_SIZE }}}) | 0;
 #if RUNTIME_DEBUG
     dbg(`growMemory: ${size} (+${size - b.byteLength} bytes / ${pages} pages)`);
 #endif
@@ -195,7 +195,7 @@ addToLibrary({
 #endif
     try {
       // round size grow request up to wasm page size (fixed 64KB per spec)
-      wasmMemory.grow(pages); // .grow() takes a delta compared to the previous size
+      wasmMemory.grow({{{ toIndexType('pages') }}}); // .grow() takes a delta compared to the previous size
       updateMemoryViews();
 #if MEMORYPROFILER
       if (typeof emscriptenMemoryProfiler != 'undefined') {