diff --git a/python/jittor/__init__.py b/python/jittor/__init__.py
index 4472a498..9f84df99 100644
--- a/python/jittor/__init__.py
+++ b/python/jittor/__init__.py
@@ -9,7 +9,7 @@
 # file 'LICENSE.txt', which is part of this source code package.
 # ***************************************************************
 
-__version__ = '1.3.1.16'
+__version__ = '1.3.1.17'
 from jittor_utils import lock
 with lock.lock_scope():
     ori_int = int
diff --git a/python/jittor/compiler.py b/python/jittor/compiler.py
index 79730ff9..80255a6b 100644
--- a/python/jittor/compiler.py
+++ b/python/jittor/compiler.py
@@ -935,6 +935,9 @@ with jit_utils.import_scope(import_flags):
     jit_utils.try_import_jit_utils_core()
 
 jittor_path = find_jittor_path()
+if os.name == 'nt':
+    # prevent windows recompile
+    jittor_path = jittor_path.lower()
 check_debug_flags()
 
 sys.path.append(cache_path)
diff --git a/python/jittor/src/misc/cpu_math.cc b/python/jittor/src/misc/cpu_math.cc
index 331d0a0f..c1cde31d 100644
--- a/python/jittor/src/misc/cpu_math.cc
+++ b/python/jittor/src/misc/cpu_math.cc
@@ -44,8 +44,8 @@ Date:  February 1996
     x = std::copysign(num, y) / dem;
   }
   /* Two steps of Newton-Raphson correction */
-  x = x - (std::erf(x) - y) / ((static_cast<T>(2.0)/static_cast<T>(std::sqrt(M_PI)))*std::exp(-x*x));
-  x = x - (std::erf(x) - y) / ((static_cast<T>(2.0)/static_cast<T>(std::sqrt(M_PI)))*std::exp(-x*x));
+  x = x - (std::erf(x) - y) / ((static_cast<T>(2.0)/static_cast<T>(std::sqrt(3.14159265358979323846)))*std::exp(-x*x));
+  x = x - (std::erf(x) - y) / ((static_cast<T>(2.0)/static_cast<T>(std::sqrt(3.14159265358979323846)))*std::exp(-x*x));
 
   return x;
 }