diff --git a/amalgamate.py b/amalgamate.py
index 1688d558..0d7a7d18 100644
--- a/amalgamate.py
+++ b/amalgamate.py
@@ -5,7 +5,7 @@ import sys
 import time
 from typing import List, Dict
 
-assert os.system("python prebuild.py") == 0
+assert os.system(f"{sys.executable} prebuild.py") == 0
 
 ROOT = 'include/pocketpy'
 PUBLIC_HEADERS = ['config.h', 'export.h', 'vmath.h', 'pocketpy.h']
diff --git a/build.sh b/build.sh
index 7dbbfc54..dffad1c6 100644
--- a/build.sh
+++ b/build.sh
@@ -8,7 +8,7 @@ if ! type -P clang >/dev/null 2>&1; then
 fi
 
 echo "> Running prebuild.py... "
-python prebuild.py
+command -v python3 >/dev/null 2>&1 && python3 prebuild.py || python prebuild.py
 
 if [ $? -ne 0 ]; then
     echo "prebuild.py failed."
diff --git a/build_darwin_libs.sh b/build_darwin_libs.sh
index fa73556c..3997a41d 100644
--- a/build_darwin_libs.sh
+++ b/build_darwin_libs.sh
@@ -1,6 +1,9 @@
 set -e
 
-python amalgamate.py
+# Use python3 if available, otherwise fall back to python
+PYTHON=$(command -v python3 >/dev/null 2>&1 && echo python3 || echo python)
+
+$PYTHON amalgamate.py
 
 rm -rf build
 mkdir build
@@ -20,4 +23,4 @@ cmake --build . --config Release
 
 cd ../
 
-python scripts/merge_built_libraries.py build
+$PYTHON scripts/merge_built_libraries.py build
diff --git a/build_ios_libs.sh b/build_ios_libs.sh
index a95ff471..010656fc 100644
--- a/build_ios_libs.sh
+++ b/build_ios_libs.sh
@@ -1,6 +1,9 @@
 set -e
 
-python amalgamate.py
+# Use python3 if available, otherwise fall back to python
+PYTHON=$(command -v python3 >/dev/null 2>&1 && echo python3 || echo python)
+
+$PYTHON amalgamate.py
 
 rm -rf build
 mkdir build
@@ -27,8 +30,8 @@ cd ../
 
 HEADERS="amalgamated/pocketpy.h"
 
-python scripts/merge_built_libraries.py build/os64
-python scripts/merge_built_libraries.py build/simulatorarm64
+$PYTHON scripts/merge_built_libraries.py build/os64
+$PYTHON scripts/merge_built_libraries.py build/simulatorarm64
 
 xcodebuild -create-xcframework \
     -library build/os64/libpocketpy.a -headers $HEADERS \
diff --git a/build_web.sh b/build_web.sh
index 799f44c2..bd42019f 100644
--- a/build_web.sh
+++ b/build_web.sh
@@ -1,6 +1,9 @@
 set -e
 
-python prebuild.py
+# Use python3 if available, otherwise fall back to python
+PYTHON=$(command -v python3 >/dev/null 2>&1 && echo python3 || echo python)
+
+$PYTHON prebuild.py
 
 rm -rf web/lib
 mkdir web/lib
diff --git a/cmake_build.py b/cmake_build.py
index 954f9650..ac568da4 100644
--- a/cmake_build.py
+++ b/cmake_build.py
@@ -2,7 +2,7 @@ import os
 import sys
 import shutil
 
-assert os.system("python prebuild.py") == 0
+assert os.system(f"{sys.executable} prebuild.py") == 0
 
 if not os.path.exists("build"):
     os.mkdir("build")
diff --git a/run_profile.sh b/run_profile.sh
index 28cc8c37..9f1af0ec 100644
--- a/run_profile.sh
+++ b/run_profile.sh
@@ -1,6 +1,9 @@
 set -e
 
-python prebuild.py
+# Use python3 if available, otherwise fall back to python
+PYTHON=$(command -v python3 >/dev/null 2>&1 && echo python3 || echo python)
+
+$PYTHON prebuild.py
 
 SRC=$(find src/ -name "*.c")
 
diff --git a/run_tests.sh b/run_tests.sh
index 6b2c46ef..a5bb5ef6 100644
--- a/run_tests.sh
+++ b/run_tests.sh
@@ -1,12 +1,15 @@
 set -e
 
-python prebuild.py
+# Use python3 if available, otherwise fall back to python
+PYTHON=$(command -v python3 >/dev/null 2>&1 && echo python3 || echo python)
+
+$PYTHON prebuild.py
 
 SRC=$(find src/ -name "*.c")
 
 clang -std=c11 --coverage -O1 -Wfatal-errors -o main src2/main.c $SRC -Iinclude -DPK_ENABLE_OS=1 -lm -ldl -DNDEBUG
 
-python scripts/run_tests.py
+$PYTHON scripts/run_tests.py
 
 # if prev error exit
 if [ $? -ne 0 ]; then
diff --git a/scripts/run_tests.py b/scripts/run_tests.py
index 9232c7e7..245ee1ab 100644
--- a/scripts/run_tests.py
+++ b/scripts/run_tests.py
@@ -2,11 +2,14 @@ import os
 import sys
 import time
 import subprocess
+import shutil
 
 
 def test_file(filepath, cpython=False):
     if cpython:
-        return os.system("python " + filepath) == 0
+        # Use python3 if available, otherwise fall back to python
+        python_cmd = shutil.which("python3") or shutil.which("python") or "python"
+        return os.system(f"{python_cmd} {filepath}") == 0
     if sys.platform == 'win32':
         code = os.system("main.exe " + filepath)
     else: