diff --git a/CMakeLists.txt b/CMakeLists.txt
index 72f5f881..2cb8eb16 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -159,8 +159,8 @@ elseif(${CMAKE_CXX_COMPILER_ID} MATCHES "Clang" AND NOT MSVC)
         add_compile_options(-fno-exceptions)
     endif()
 
-    if(NOT CMAKE_SYSTEM_NAME STREQUAL "OpenBSD")
-        # Error if there's symbols that are not found at link time.
+    if(NOT (CMAKE_SYSTEM_NAME STREQUAL "OpenBSD" OR CMAKE_SYSTEM_NAME STREQUAL "Emscripten"))
+        # Error if there's symbols that are not found at link time. Some linkers do not support this flag.
         if (CMAKE_CXX_COMPILER_ID STREQUAL "AppleClang")
             add_link_options("-Wl,-undefined,error")
         elseif(NOT APPLE)
diff --git a/glslang/OSDependent/Web/CMakeLists.txt b/glslang/OSDependent/Web/CMakeLists.txt
index 5bfbed41..6232b809 100644
--- a/glslang/OSDependent/Web/CMakeLists.txt
+++ b/glslang/OSDependent/Web/CMakeLists.txt
@@ -53,6 +53,9 @@ if(ENABLE_GLSLANG_JS)
         target_link_libraries(glslang.js "-s ALLOW_MEMORY_GROWTH=1")
         target_link_libraries(glslang.js "-s FILESYSTEM=0")
 
+        # We use ccall in glslang.pre.js, so make sure it's exposed
+        target_link_libraries(glslang.js "-s EXPORTED_RUNTIME_METHODS=ccall")
+
         if(ENABLE_EMSCRIPTEN_SINGLE_FILE)
             target_link_libraries(glslang.js "-s SINGLE_FILE=1")
         endif()
@@ -64,8 +67,18 @@ if(ENABLE_GLSLANG_JS)
         endif()
 
         if(NOT ENABLE_EMSCRIPTEN_ENVIRONMENT_NODE)
-            add_custom_command(TARGET glslang.js POST_BUILD
-                COMMAND cat ${CMAKE_CURRENT_SOURCE_DIR}/glslang.after.js >> ${CMAKE_CURRENT_BINARY_DIR}/glslang.js)
+            if (CMAKE_HOST_SYSTEM MATCHES "Windows.*")
+                # There are several ways we could append one file to another on Windows, but unfortunately 'cat' is not one of them
+                # (there is no 'cat' command in cmd). Also, since this will ultimately run in cmd and not pwsh, we need to ensure
+                # Windows path separators are used.
+                file(TO_NATIVE_PATH "${CMAKE_CURRENT_BINARY_DIR}/glslang.js" glslang_js_path)
+                file(TO_NATIVE_PATH "${CMAKE_CURRENT_SOURCE_DIR}/glslang.after.js" glslang_after_js_path)
+                add_custom_command(TARGET glslang.js POST_BUILD
+                    COMMAND type "${glslang_after_js_path}" >> "${glslang_js_path}")
+            else()
+                add_custom_command(TARGET glslang.js POST_BUILD
+                    COMMAND cat ${CMAKE_CURRENT_SOURCE_DIR}/glslang.after.js >> ${CMAKE_CURRENT_BINARY_DIR}/glslang.js)
+            endif()
         endif()
     endif()
 endif()
diff --git a/glslang/OSDependent/Web/glslang.pre.js b/glslang/OSDependent/Web/glslang.pre.js
index 46a56950..390390e9 100644
--- a/glslang/OSDependent/Web/glslang.pre.js
+++ b/glslang/OSDependent/Web/glslang.pre.js
@@ -25,7 +25,7 @@ Module['compileGLSLZeroCopy'] = function(glsl, shader_stage, gen_debug, spirv_ve
 
     var p_output = Module['_malloc'](4);
     var p_output_len = Module['_malloc'](4);
-    var id = ccall('convert_glsl_to_spirv',
+    var id = Module['ccall']('convert_glsl_to_spirv',
         'number',
         ['string', 'number', 'boolean', 'number', 'number', 'number'],
         [glsl, shader_stage_int, gen_debug, spirv_version_int, p_output, p_output_len]);