diff --git a/craft_parts/executor/step_handler.py b/craft_parts/executor/step_handler.py
index 5eab915..bc26252 100644
--- a/craft_parts/executor/step_handler.py
+++ b/craft_parts/executor/step_handler.py
@@ -445,7 +445,8 @@ def _create_and_run_script(
 ) -> None:
     """Create a script with step-specific commands and execute it."""
     with script_path.open("w") as run_file:
-        print("#!/bin/bash", file=run_file)
+        import shutil
+        print(f"#!{shutil.which('bash')}", file=run_file)
         print("set -euo pipefail", file=run_file)
 
         if environment_script_path:
diff --git a/craft_parts/plugins/java_plugin.py b/craft_parts/plugins/java_plugin.py
index f2b4064..cb4e9e8 100644
--- a/craft_parts/plugins/java_plugin.py
+++ b/craft_parts/plugins/java_plugin.py
@@ -71,9 +71,8 @@ class JavaPlugin(Plugin):
         return None, ""
 
     def _find_javac(self) -> list[str]:
-        cmd = ["find", "/usr/lib/jvm", "-path", "*/bin/javac", "-print"]
-        output = subprocess.check_output(cmd, text=True)
-        return [x for x in output.split("\n") if len(x) > 0]
+        import shutil
+        return [shutil.which("javac")]
 
     @override
     def get_build_environment(self) -> dict[str, str]:
diff --git a/craft_parts/plugins/validator.py b/craft_parts/plugins/validator.py
index 5b4c735..d7a446e 100644
--- a/craft_parts/plugins/validator.py
+++ b/craft_parts/plugins/validator.py
@@ -142,8 +142,9 @@ class PluginEnvironmentValidator:
             print(cmd, file=env_file)
             env_file.flush()
 
+            import shutil
             proc = subprocess.run(
-                ["/bin/bash", env_file.name],
+                [shutil.which("bash"), env_file.name],
                 check=True,
                 capture_output=True,
                 text=True,
diff --git a/tests/unit/executor/test_step_handler.py b/tests/unit/executor/test_step_handler.py
index 4e73c2b..a5f9374 100644
--- a/tests/unit/executor/test_step_handler.py
+++ b/tests/unit/executor/test_step_handler.py
@@ -209,9 +209,10 @@ class TestStepHandlerBuiltins:
 
         assert get_mode(build_script_path) == 0o755
         with open(build_script_path) as file:
+            import shutil
             assert file.read() == dedent(
                 f"""\
-                #!/bin/bash
+                #!{shutil.which("bash")}
                 set -euo pipefail
                 source {environment_script_path}
                 set -x
diff --git a/tests/unit/utils/test_process.py b/tests/unit/utils/test_process.py
index a025494..a76cfa2 100644
--- a/tests/unit/utils/test_process.py
+++ b/tests/unit/utils/test_process.py
@@ -33,7 +33,8 @@ _RUN_TEST_CASES = [
 
 @pytest.mark.parametrize(("out", "err"), _RUN_TEST_CASES)
 def test_run(out, err):
-    result = process.run(["/usr/bin/sh", "-c", f"echo {out};sleep 0.1;echo {err} >&2"])
+    import shutil
+    result = process.run([shutil.which("sh"), "-c", f"echo {out};sleep 0.1;echo {err} >&2"])
     assert result.returncode == 0
     assert result.stdout == (out + "\n").encode()
     assert result.stderr == (err + "\n").encode()
@@ -42,8 +43,9 @@ def test_run(out, err):
 
 @pytest.mark.parametrize(("out", "err"), _RUN_TEST_CASES)
 def test_run_devnull(out, err):
+    import shutil
     result = process.run(
-        ["/usr/bin/sh", "-c", f"echo {out};echo {err} >&2"],
+        [shutil.which("sh"), "-c", f"echo {out};echo {err} >&2"],
         stdout=subprocess.DEVNULL,
         stderr=subprocess.DEVNULL,
     )
@@ -78,9 +80,10 @@ def test_run_selector(out, err, new_dir):
 
     selector.register(sock, selectors.EVENT_READ, accept)
 
+    import shutil
     result = process.run(
         [
-            "/usr/bin/sh",
+            shutil.which("sh"),
             "-c",
             f"echo {out};sleep 0.1;echo {err} >&2; echo -n {out}|socat - UNIX-CONNECT:{new_dir}/test.socket",
         ],