diff --git a/scripts/generate_psa_constants.py b/scripts/generate_psa_constants.py
index 71afd02..960a079 100755
--- a/scripts/generate_psa_constants.py
+++ b/scripts/generate_psa_constants.py
@@ -29,6 +29,7 @@
 import os
 import sys
 
+from mbedtls_dev import build_tree
 from mbedtls_dev import macro_collector
 
 OUTPUT_TEMPLATE = '''\
@@ -335,8 +336,7 @@
     os.replace(temp_file_name, output_file_name)
 
 if __name__ == '__main__':
-    if not os.path.isdir('programs') and os.path.isdir('../programs'):
-        os.chdir('..')
+    build_tree.chdir_to_root()
     # Allow to change the directory where psa_constant_names_generated.c is written to.
     OUTPUT_FILE_DIR = sys.argv[1] if len(sys.argv) == 2 else "programs/psa"
     generate_psa_constants(['include/psa/crypto_values.h',
diff --git a/scripts/generate_query_config.pl b/scripts/generate_query_config.pl
index 3cef101..8c8c188 100755
--- a/scripts/generate_query_config.pl
+++ b/scripts/generate_query_config.pl
@@ -38,6 +38,12 @@
 my $query_config_format_file = "./scripts/data_files/query_config.fmt";
 my $query_config_file = "./programs/test/query_config.c";
 
+unless( -f $config_file && -f $query_config_format_file ) {
+    chdir '..' or die;
+    -f $config_file && -f $query_config_format_file
+      or die "Without arguments, must be run from root or a subdirectory\n";
+}
+
 # Excluded macros from the generated query_config.c. For example, macros that
 # have commas or function-like macros cannot be transformed into strings easily
 # using the preprocessor, so they should be excluded or the preprocessor will
diff --git a/scripts/mbedtls_dev/build_tree.py b/scripts/mbedtls_dev/build_tree.py
new file mode 100644
index 0000000..7724104
--- /dev/null
+++ b/scripts/mbedtls_dev/build_tree.py
@@ -0,0 +1,38 @@
+"""Mbed TLS build tree information and manipulation.
+"""
+
+# Copyright The Mbed TLS Contributors
+# SPDX-License-Identifier: Apache-2.0
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import os
+
+def looks_like_mbedtls_root(path: str) -> bool:
+    """Whether the given directory looks like the root of the Mbed TLS source tree."""
+    return all(os.path.isdir(os.path.join(path, subdir))
+               for subdir in ['include', 'library', 'programs', 'tests'])
+
+def chdir_to_root() -> None:
+    """Detect the root of the Mbed TLS source tree and change to it.
+
+    The current directory must be up to two levels deep inside an Mbed TLS
+    source tree.
+    """
+    for d in [os.path.curdir,
+              os.path.pardir,
+              os.path.join(os.path.pardir, os.path.pardir)]:
+        if looks_like_mbedtls_root(d):
+            os.chdir(d)
+            return
+    raise Exception('Mbed TLS source tree not found')
diff --git a/tests/scripts/generate_psa_tests.py b/tests/scripts/generate_psa_tests.py
index 669c75d..ab8ebff 100755
--- a/tests/scripts/generate_psa_tests.py
+++ b/tests/scripts/generate_psa_tests.py
@@ -27,6 +27,7 @@
 from typing import Callable, Dict, FrozenSet, Iterable, Iterator, List, Optional, TypeVar
 
 import scripts_path # pylint: disable=unused-import
+from mbedtls_dev import build_tree
 from mbedtls_dev import crypto_knowledge
 from mbedtls_dev import macro_collector
 from mbedtls_dev import psa_storage
@@ -79,9 +80,13 @@
     return frozenset(symbol
                      for line in open(filename)
                      for symbol in re.findall(r'\bPSA_WANT_\w+\b', line))
-IMPLEMENTED_DEPENDENCIES = read_implemented_dependencies('include/psa/crypto_config.h')
+_implemented_dependencies = None #type: Optional[FrozenSet[str]] #pylint: disable=invalid-name
 def hack_dependencies_not_implemented(dependencies: List[str]) -> None:
-    if not all(dep.lstrip('!') in IMPLEMENTED_DEPENDENCIES
+    global _implemented_dependencies #pylint: disable=global-statement,invalid-name
+    if _implemented_dependencies is None:
+        _implemented_dependencies = \
+            read_implemented_dependencies('include/psa/crypto_config.h')
+    if not all(dep.lstrip('!') in _implemented_dependencies
                for dep in dependencies):
         dependencies.append('DEPENDENCY_NOT_IMPLEMENTED_YET')
 
@@ -426,6 +431,7 @@
     parser.add_argument('targets', nargs='*', metavar='TARGET',
                         help='Target file to generate (default: all; "-": none)')
     options = parser.parse_args(args)
+    build_tree.chdir_to_root()
     generator = TestGenerator(options)
     if options.list:
         for name in sorted(generator.TARGETS):