diff --git a/var/spack/repos/builtin/packages/bazel/package.py b/var/spack/repos/builtin/packages/bazel/package.py
index c4d3ca841c7..bdb980cc63b 100644
--- a/var/spack/repos/builtin/packages/bazel/package.py
+++ b/var/spack/repos/builtin/packages/bazel/package.py
@@ -319,7 +319,7 @@ def install_test(self):
                 )
 
             # Spack's logs don't handle colored output well
-            bazel = Executable(self.spec["bazel"].command.path)
+            bazel = Executable(self.command.path)
             bazel(
                 "--output_user_root=/tmp/spack/bazel/spack-test",
                 "build",
@@ -332,7 +332,7 @@ def install_test(self):
             assert exe(output=str) == "Hi!\n"
 
     def setup_dependent_package(self, module, dependent_spec):
-        module.bazel = Executable(self.spec["bazel"].command.path)
+        module.bazel = Executable(self.command.path)
 
     @property
     def parallel(self):
diff --git a/var/spack/repos/builtin/packages/cosmomc/package.py b/var/spack/repos/builtin/packages/cosmomc/package.py
index db0fc69eddc..933dfd99768 100644
--- a/var/spack/repos/builtin/packages/cosmomc/package.py
+++ b/var/spack/repos/builtin/packages/cosmomc/package.py
@@ -169,7 +169,7 @@ def check_install(self):
         os.environ.pop("CLIKPATH", "")
         os.environ.pop("PLANCKLIKE", "")
 
-        exe = spec["cosmomc"].command.path
+        exe = self.command.path
         args = []
         if spec.satisfies("+mpi"):
             # Add mpirun prefix
diff --git a/var/spack/repos/builtin/packages/gcc/package.py b/var/spack/repos/builtin/packages/gcc/package.py
index b5767c60538..9566b4db95c 100644
--- a/var/spack/repos/builtin/packages/gcc/package.py
+++ b/var/spack/repos/builtin/packages/gcc/package.py
@@ -1005,7 +1005,7 @@ def write_specs_file(self):
         specs_file = join_path(self.spec_dir, "specs")
         with open(specs_file, "w") as f:
             # can't extend the builtins without dumping them first
-            f.write(self.spec["gcc"].command("-dumpspecs", output=str, error=os.devnull).strip())
+            f.write(self.command("-dumpspecs", output=str, error=os.devnull).strip())
 
             f.write("\n\n# Generated by Spack\n\n")
 
@@ -1179,7 +1179,7 @@ def _post_buildcache_install_hook(self):
 
         # Setting up the runtime environment shouldn't be necessary here.
         relocation_args = []
-        gcc = self.spec["gcc"].command
+        gcc = self.command
         specs_file = os.path.join(self.spec_dir, "specs")
         dryrun = gcc("test.c", "-###", output=os.devnull, error=str).strip()
         if not dryrun:
diff --git a/var/spack/repos/builtin/packages/go/package.py b/var/spack/repos/builtin/packages/go/package.py
index 05196d7616b..fef03bec1c4 100644
--- a/var/spack/repos/builtin/packages/go/package.py
+++ b/var/spack/repos/builtin/packages/go/package.py
@@ -120,4 +120,4 @@ def setup_dependent_package(self, module, dependent_spec):
         install_tree('bin', prefix.bin)
         """
         #  Add a go command/compiler for extensions
-        module.go = self.spec["go"].command
+        module.go = self.command
diff --git a/var/spack/repos/builtin/packages/jq/package.py b/var/spack/repos/builtin/packages/jq/package.py
index 098963a74fc..fc4b1c89ae5 100644
--- a/var/spack/repos/builtin/packages/jq/package.py
+++ b/var/spack/repos/builtin/packages/jq/package.py
@@ -36,7 +36,7 @@ def configure_args(self):
     @run_after("install")
     @on_package_attributes(run_tests=True)
     def install_test(self):
-        jq = self.spec["jq"].command
+        jq = self.command
         f = os.path.join(os.path.dirname(__file__), "input.json")
 
         assert jq(".bar", input=f, output=str) == "2\n"
diff --git a/var/spack/repos/builtin/packages/plumed/package.py b/var/spack/repos/builtin/packages/plumed/package.py
index 04041f43df5..07b29affeee 100644
--- a/var/spack/repos/builtin/packages/plumed/package.py
+++ b/var/spack/repos/builtin/packages/plumed/package.py
@@ -244,7 +244,7 @@ def apply_patch(self, other):
 
     def setup_dependent_package(self, module, dependent_spec):
         # Make plumed visible from dependent packages
-        module.plumed = dependent_spec["plumed"].command
+        module.plumed = self.command
 
     @property
     def plumed_inc(self):
diff --git a/var/spack/repos/builtin/packages/python-venv/package.py b/var/spack/repos/builtin/packages/python-venv/package.py
index 796419a5ff6..583c3fafbd5 100644
--- a/var/spack/repos/builtin/packages/python-venv/package.py
+++ b/var/spack/repos/builtin/packages/python-venv/package.py
@@ -54,7 +54,7 @@ def bindir(self):
     def command(self):
         """Returns a python Executable instance"""
         python_name = "python" if self.spec.satisfies("platform=windows") else "python3"
-        return which(python_name, path=self.bindir)
+        return which(python_name, path=self.bindir, required=True)
 
     def _get_path(self, name) -> str:
         return self.command(
diff --git a/var/spack/repos/builtin/packages/python/package.py b/var/spack/repos/builtin/packages/python/package.py
index 322744dc0a5..f86e3570f34 100644
--- a/var/spack/repos/builtin/packages/python/package.py
+++ b/var/spack/repos/builtin/packages/python/package.py
@@ -1373,8 +1373,7 @@ def add_files_to_view(self, view, merge_map, skip_if_exists=True):
 
     def test_hello_world(self):
         """run simple hello world program"""
-        # do not use self.command because we are also testing the run env
-        python = self.spec["python"].command
+        python = self.command
 
         msg = "hello world!"
         out = python("-c", f'print("{msg}")', output=str.split, error=str.split)
@@ -1382,7 +1381,7 @@ def test_hello_world(self):
 
     def test_import_executable(self):
         """ensure import of installed executable works"""
-        python = self.spec["python"].command
+        python = self.command
 
         out = python("-c", "import sys; print(sys.executable)", output=str.split, error=str.split)
         assert self.spec.prefix in out