diff --git a/CMakeLists.txt b/CMakeLists.txt
index 71345e74..235c3f79 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -354,7 +354,8 @@ if(WEBP_BUILD_WEBP_JS)
   target_link_libraries(webp_js webpdecoder SDL)
   set(WEBP_HAVE_SDL 1)
   set_target_properties(webp_js PROPERTIES LINK_FLAGS
-      "-s EXPORTED_FUNCTIONS='[\"_WebpToSDL\"]' -s INVOKE_RUN=0")
+      "-s EXPORTED_FUNCTIONS='[\"_WebpToSDL\"]' -s INVOKE_RUN=0 \
+       -s EXTRA_EXPORTED_RUNTIME_METHODS='[\"cwrap\"]'")
   set_target_properties(webp_js PROPERTIES OUTPUT_NAME webp)
   target_compile_definitions(webp_js PUBLIC EMSCRIPTEN WEBP_HAVE_SDL)
 
@@ -364,7 +365,8 @@ if(WEBP_BUILD_WEBP_JS)
   target_link_libraries(webp_wasm webpdecoder SDL)
   set_target_properties(webp_wasm PROPERTIES LINK_FLAGS
       "-s WASM=1 -s 'BINARYEN_METHOD=\"native-wasm\"' \
-      -s EXPORTED_FUNCTIONS='[\"_WebpToSDL\"]' -s INVOKE_RUN=0")
+       -s EXPORTED_FUNCTIONS='[\"_WebpToSDL\"]' -s INVOKE_RUN=0 \
+       -s EXTRA_EXPORTED_RUNTIME_METHODS='[\"cwrap\"]'")
   target_compile_definitions(webp_wasm PUBLIC EMSCRIPTEN WEBP_HAVE_SDL)
 
   target_compile_definitions(webpdecoder PUBLIC EMSCRIPTEN)
diff --git a/README.webp_js b/README.webp_js
index 04f4970b..2805354d 100644
--- a/README.webp_js
+++ b/README.webp_js
@@ -32,7 +32,8 @@ using Emscripten and CMake.
    webp.js.mem files generated.
 
 The callable JavaScript function is WebPToSDL(), which decodes a raw WebP
-bitstream into a canvas. See webp_js/index.html for a simple usage sample.
+bitstream into a canvas. See webp_js/index.html for a simple usage sample
+(see below for instructions).
 
 Demo HTML page:
 ===============