diff --git a/emscripten.py b/emscripten.py
index 835b1ec97..bf55ee43f 100755
--- a/emscripten.py
+++ b/emscripten.py
@@ -1076,8 +1076,9 @@ def emscript_fast(infile, settings, outfile, libraries=[], compiler_engine=None,
   }
 ''' % (sig, ',' if len(sig) > 1 else '', args, arg_coercions, ret))
 
+      ffi_args = ','.join([shared.JS.make_coercion('a' + str(i), sig[i], settings, ffi_arg=True) for i in range(1, len(sig))])
       for i in range(settings['RESERVED_FUNCTION_POINTERS']):
-        jsret = ('return ' if sig[0] != 'v' else '') + shared.JS.make_coercion('jsCall(%d%s%s)' % (i, ',' if coerced_args else '', coerced_args), sig[0], settings)
+        jsret = ('return ' if sig[0] != 'v' else '') + shared.JS.make_coercion('jsCall(%d%s%s)' % (i, ',' if ffi_args else '', ffi_args), sig[0], settings, ffi_result=True)
         function_tables_impls.append('''
   function jsCall_%s_%s(%s) {
     %s
diff --git a/tools/shared.py b/tools/shared.py
index 82bdd98b9..826baa832 100644
--- a/tools/shared.py
+++ b/tools/shared.py
@@ -1650,12 +1650,17 @@ class JS:
       return '+0'
 
   @staticmethod
-  def make_coercion(value, sig, settings=None):
+  def make_coercion(value, sig, settings=None, ffi_arg=False, ffi_result=False):
     settings = settings or Settings
     if sig == 'i':
       return value + '|0'
     elif sig == 'f' and settings.get('PRECISE_F32'):
-      return 'Math_fround(' + value + ')'
+      if ffi_arg:
+        return '+Math_fround(' + value + ')'
+      elif ffi_result:
+        return 'Math_fround(+(' + value + '))'
+      else:
+        return 'Math_fround(' + value + ')'
     elif sig == 'd' or sig == 'f':
       return '+' + value
     else: