diff --git a/emscripten.py b/emscripten.py
index 2e727d517..257527fe1 100755
--- a/emscripten.py
+++ b/emscripten.py
@@ -483,6 +483,9 @@ def emscript(infile, settings, outfile, libraries=[], compiler_engine=None,
       shared.Settings.copy(settings)
       asm_setup += '\n' + shared.JS.make_invoke(sig) + '\n'
       basic_funcs.append('invoke_%s' % sig)
+      if settings.get('DLOPEN_SUPPORT'):
+        asm_setup += '\n' + shared.JS.make_extcall(sig) + '\n'
+        basic_funcs.append('extCall_%s' % sig)
 
     # calculate exports
     exported_implemented_functions = list(exported_implemented_functions)
diff --git a/src/jsifier.js b/src/jsifier.js
index ce08fdded..8592364d6 100644
--- a/src/jsifier.js
+++ b/src/jsifier.js
@@ -1405,8 +1405,10 @@ function JSify(data, functionsOnly, givenFunctions) {
     // We cannot compile assembly. See comment in intertyper.js:'Call'
     assert(ident != 'asm', 'Inline assembly cannot be compiled to JavaScript!');
 
+    var extCall = false;
+
     if (ASM_JS && funcData.setjmpTable) forceByPointer = true; // in asm.js mode, we must do an invoke for each call
-    if (ASM_JS && DLOPEN_SUPPORT) invoke = true; // go through invoke so we can access other modules TODO: optimize
+    if (ASM_JS && DLOPEN_SUPPORT && !invoke) extCall = true; // go out, to be able to access other modules TODO: optimize
 
     ident = Variables.resolveAliasToIdent(ident);
     var shortident = ident.slice(1);
@@ -1467,7 +1469,7 @@ function JSify(data, functionsOnly, givenFunctions) {
 
     args = args.map(function(arg, i) { return indexizeFunctions(arg, argsTypes[i]) });
     if (ASM_JS) {
-      if (shortident in Functions.libraryFunctions || simpleIdent in Functions.libraryFunctions || byPointerForced || invoke || funcData.setjmpTable) {
+      if (shortident in Functions.libraryFunctions || simpleIdent in Functions.libraryFunctions || byPointerForced || invoke || extCall || funcData.setjmpTable) {
         args = args.map(function(arg, i) { return asmCoercion(arg, argsTypes[i]) });
       } else {
         args = args.map(function(arg, i) { return asmEnsureFloat(arg, argsTypes[i]) });
@@ -1558,16 +1560,16 @@ function JSify(data, functionsOnly, givenFunctions) {
       if (ASM_JS) {
         assert(returnType.search(/\("'\[,/) == -1); // XXX need isFunctionType(type, out)
         Functions.neededTables[sig] = 1;
-        var functionTableCall = !byPointerForced && !funcData.setjmpTable && !invoke;
+        var functionTableCall = !byPointerForced && !funcData.setjmpTable && !invoke && !extCall;
         if (functionTableCall) {
           // normal asm function pointer call
           callIdent = '(' + callIdent + ')&{{{ FTM_' + sig + ' }}}'; // the function table mask is set in emscripten.py
         } else {
-          // This is a call through an invoke_*, either a forced one, or a setjmp-required one
+          // This is a call through an invoke_* or extCall, either a forced one, or a setjmp-required one
           // note: no need to update argsTypes at this point
           if (byPointerForced) Functions.unimplementedFunctions[callIdent] = sig;
           args.unshift(byPointerForced ? Functions.getIndex(callIdent, sig) : asmCoercion(callIdent, 'i32'));
-          callIdent = 'invoke_' + sig;
+          callIdent = (extCall ? 'extCall' : 'invoke') + '_' + sig;
         }
       } else if (SAFE_DYNCALLS) {
         assert(!ASM_JS, 'cannot emit safe dyncalls in asm');
diff --git a/tools/shared.py b/tools/shared.py
index aecf07993..b0b3985e9 100644
--- a/tools/shared.py
+++ b/tools/shared.py
@@ -1442,6 +1442,27 @@ class JS:
   def to_nice_ident(ident): # limited version of the JS function toNiceIdent
     return ident.replace('%', '$').replace('@', '_')
 
+  @staticmethod
+  def make_extcall(sig, named=True):
+    args = ','.join(['a' + str(i) for i in range(1, len(sig))])
+    args = 'index' + (',' if args else '') + args
+    # C++ exceptions are numbers, and longjmp is a string 'longjmp'
+    ret = '''function%s(%s) {
+  %sModule["dynCall_%s"](%s);
+}''' % ((' extCall_' + sig) if named else '', args, 'return ' if sig[0] != 'v' else '', sig, args)
+
+    if Settings.DLOPEN_SUPPORT and Settings.ASSERTIONS:
+      # guard against cross-module stack leaks
+      ret = ret.replace(') {\n', ''') {
+  try {
+    var preStack = asm.stackSave();
+''').replace(';\n}', ''';
+  } finally {
+    assert(asm.stackSave() == preStack);
+  }
+}''')
+    return ret
+
   @staticmethod
   def make_invoke(sig, named=True):
     args = ','.join(['a' + str(i) for i in range(1, len(sig))])