diff --git a/script/build_spec.py b/script/build_spec.py
index 76b6d0d..5230edd 100644
--- a/script/build_spec.py
+++ b/script/build_spec.py
@@ -20,6 +20,8 @@ def cd(dst: str) -> typing.Generator[None, typing.Any, None]:
 
 root = os.path.dirname(os.path.dirname(__file__))
 os.chdir(root)
+wast2json = f'{root}/res/wabt/bin/wast2json'
+
 
 with cd('res'):
     if not os.path.exists('spec'):
@@ -32,7 +34,7 @@ def cd(dst: str) -> typing.Generator[None, typing.Any, None]:
     call('git checkout fffc6e12fa454e475455a7b58d3b5dc343980c10')
 with cd('res/spec/test/core'):
     for e in sorted(glob.glob('*.wast')):
-        call(f'{root}/res/wabt/bin/wast2json {e}')
+        call(f'{wast2json} {e}')
 with cd('res/spec/test/core/simd'):
     for e in sorted(glob.glob('*.wast')):
-        call(f'{root}/res/wabt/bin/wast2json {e}')
+        call(f'{wast2json} {e}')
diff --git a/script/build_wabt.py b/script/build_wabt.py
index 4a25949..375d71b 100644
--- a/script/build_wabt.py
+++ b/script/build_wabt.py
@@ -20,6 +20,9 @@ def cd(dst: str) -> typing.Generator[None, typing.Any, None]:
     os.chdir(cwd)
 
 
+root = os.path.dirname(os.path.dirname(__file__))
+os.chdir(root)
+
 version = '1.0.37'
 url = ''
 match platform.system().lower():
diff --git a/script/build_wasi.py b/script/build_wasi.py
index 5b53d0a..18fc44e 100644
--- a/script/build_wasi.py
+++ b/script/build_wasi.py
@@ -17,6 +17,9 @@ def cd(dst: str) -> typing.Generator[None, typing.Any, None]:
     os.chdir(cwd)
 
 
+root = os.path.dirname(os.path.dirname(__file__))
+os.chdir(root)
+
 with cd('res'):
     if not os.path.exists('wasi-testsuite'):
         call('git clone --branch prod/testsuite-base https://github.com/WebAssembly/wasi-testsuite')