diff --git a/cwltool/job.py b/cwltool/job.py
index 55c8cfc87..d1950154b 100644
--- a/cwltool/job.py
+++ b/cwltool/job.py
@@ -190,7 +190,7 @@ def is_streamable(file: str) -> bool:
                 return False
             for inp in self.joborder.values():
                 if isinstance(inp, dict) and inp.get("location", None) == file:
-                    return inp.get("streamable", False)
+                    return cast(bool, inp.get("streamable", False))
             return False
 
         for knownfile in self.pathmapper.files():
diff --git a/mypy.ini b/mypy.ini
index bac992869..b99f97b82 100644
--- a/mypy.ini
+++ b/mypy.ini
@@ -5,6 +5,7 @@ show_column_numbers = true
 show_error_codes = true
 pretty = true
 warn_unreachable = True
+new_type_inference = True
 
 [mypy-galaxy.tool_util.*]
 ignore_missing_imports = True
diff --git a/setup.py b/setup.py
index e3509504c..c32b773ec 100644
--- a/setup.py
+++ b/setup.py
@@ -85,7 +85,7 @@
         "cwltool/workflow.py",
     ]
 
-    from mypyc.build import mypycify  # type: ignore[import]
+    from mypyc.build import mypycify  # type: ignore[import-untyped]
 
     opt_level = os.getenv("MYPYC_OPT_LEVEL", "3")
     ext_modules = mypycify(mypyc_targets, opt_level=opt_level)