diff --git a/programs/.gitignore b/programs/.gitignore
index 44e904a95..398152dcb 100644
--- a/programs/.gitignore
+++ b/programs/.gitignore
@@ -64,6 +64,7 @@ test/cpp_dummy_build.cpp
 test/dlopen
 test/ecp-bench
 test/query_compile_time_config
+test/query_included_headers
 test/selftest
 test/ssl_cert_test
 test/udp_proxy
diff --git a/programs/Makefile b/programs/Makefile
index fdfece72a..3509fc374 100644
--- a/programs/Makefile
+++ b/programs/Makefile
@@ -123,6 +123,7 @@ APPS = \
 	ssl/ssl_server2 \
 	test/benchmark \
 	test/query_compile_time_config \
+	test/query_included_headers \
 	test/selftest \
 	test/udp_proxy \
 	test/zeroize \
@@ -403,6 +404,10 @@ test/query_config.o: test/query_config.c test/query_config.h $(DEP)
 	echo "  CC    test/query_config.c"
 	$(CC) $(LOCAL_CFLAGS) $(CFLAGS) -c test/query_config.c -o $@
 
+test/query_included_headers$(EXEXT): test/query_included_headers.c $(DEP)
+	echo "  CC    test/query_included_headers.c"
+	$(CC) $(LOCAL_CFLAGS) $(CFLAGS) test/query_included_headers.c    $(LOCAL_LDFLAGS) $(LDFLAGS) -o $@
+
 test/selftest$(EXEXT): test/selftest.c $(DEP)
 	echo "  CC    test/selftest.c"
 	$(CC) $(LOCAL_CFLAGS) $(CFLAGS) test/selftest.c    $(LOCAL_LDFLAGS) $(LDFLAGS) -o $@
diff --git a/programs/test/CMakeLists.txt b/programs/test/CMakeLists.txt
index c3e7d2e98..735684ebf 100644
--- a/programs/test/CMakeLists.txt
+++ b/programs/test/CMakeLists.txt
@@ -3,6 +3,7 @@ set(libs
 )
 
 set(executables_libs
+    query_included_headers
     selftest
     udp_proxy
 )
diff --git a/programs/test/query_included_headers.c b/programs/test/query_included_headers.c
new file mode 100644
index 000000000..383a2ffc8
--- /dev/null
+++ b/programs/test/query_included_headers.c
@@ -0,0 +1,41 @@
+/* Ad hoc report on included headers. */
+/*
+ *  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.
+ */
+
+#include <psa/crypto.h>
+#include <mbedtls/platform.h>
+
+int main(void)
+{
+
+    /* Which PSA platform header? */
+#if defined(PSA_CRYPTO_PLATFORM_H)
+    mbedtls_printf("PSA_CRYPTO_PLATFORM_H\n");
+#endif
+#if defined(PSA_CRYPTO_PLATFORM_ALT_H)
+    mbedtls_printf("PSA_CRYPTO_PLATFORM_ALT_H\n");
+#endif
+
+    /* Which PSA struct header? */
+#if defined(PSA_CRYPTO_STRUCT_H)
+    mbedtls_printf("PSA_CRYPTO_STRUCT_H\n");
+#endif
+#if defined(PSA_CRYPTO_STRUCT_ALT_H)
+    mbedtls_printf("PSA_CRYPTO_STRUCT_ALT_H\n");
+#endif
+
+}
diff --git a/tests/.gitignore b/tests/.gitignore
index 15fce6888..b85d66aa4 100644
--- a/tests/.gitignore
+++ b/tests/.gitignore
@@ -13,6 +13,8 @@ data_files/hmac_drbg_seed
 data_files/ctr_drbg_seed
 data_files/entropy_seed
 
+include/alt-extra/psa/crypto_platform_alt.h
+include/alt-extra/psa/crypto_struct_alt.h
 include/test/instrument_record_status.h
 
 src/*.o
diff --git a/tests/Makefile b/tests/Makefile
index c9283c984..26947f4b9 100644
--- a/tests/Makefile
+++ b/tests/Makefile
@@ -219,6 +219,7 @@ ifndef WINDOWS
 	rm -rf $(BINARIES) *.c *.datax
 	rm -f src/*.o src/drivers/*.o src/libmbed*
 	rm -f include/test/instrument_record_status.h
+	rm -f include/alt-extra/*/*_alt.h
 	rm -rf libtestdriver1
 	rm -f ../library/libtestdriver1.a
 else
@@ -244,6 +245,10 @@ check: $(BINARIES)
 
 test: check
 
+# Generate variants of some headers for testing
+include/alt-extra/%_alt.h: ../include/%.h
+	perl -p -e 's/^(# *(define|ifndef) +\w+_)H\b/$${1}ALT_H/' $< >$@
+
 # Generate test library
 
 # Perl code that is executed to transform each original line from a library
diff --git a/tests/include/alt-extra/psa/crypto.h b/tests/include/alt-extra/psa/crypto.h
new file mode 100644
index 000000000..005f3aeea
--- /dev/null
+++ b/tests/include/alt-extra/psa/crypto.h
@@ -0,0 +1,7 @@
+/* The goal of the include/alt-extra directory is to test what happens
+ * if certain files come _after_ the normal include directory.
+ * Make sure that if the alt-extra directory comes before the normal
+ * directory (so we wouldn't be achieving our test objective), the build
+ * will fail.
+ */
+#error "The normal include directory must come first in the include path"
diff --git a/tests/scripts/all.sh b/tests/scripts/all.sh
index 7d91fa27d..a851d0e7b 100755
--- a/tests/scripts/all.sh
+++ b/tests/scripts/all.sh
@@ -3258,6 +3258,27 @@ component_build_psa_config_file () {
     rm -f psa_test_config.h psa_user_config.h
 }
 
+component_build_psa_alt_headers () {
+    msg "build: make with PSA alt headers" # ~20s
+
+    # Generate alternative versions of the substitutable headers with the
+    # same content except different include guards.
+    make -C tests include/alt-extra/psa/crypto_platform_alt.h include/alt-extra/psa/crypto_struct_alt.h
+
+    # Build the library and some programs.
+    # Don't build the fuzzers to avoid having to go through hoops to set
+    # a correct include path for programs/fuzz/Makefile.
+    make CFLAGS="-I ../tests/include/alt-extra -DMBEDTLS_PSA_CRYPTO_PLATFORM_FILE='\"psa/crypto_platform_alt.h\"' -DMBEDTLS_PSA_CRYPTO_STRUCT_FILE='\"psa/crypto_struct_alt.h\"'" lib
+    make -C programs -o fuzz CFLAGS="-I ../tests/include/alt-extra -DMBEDTLS_PSA_CRYPTO_PLATFORM_FILE='\"psa/crypto_platform_alt.h\"' -DMBEDTLS_PSA_CRYPTO_STRUCT_FILE='\"psa/crypto_struct_alt.h\"'"
+
+    # Check that we're getting the alternative include guards and not the
+    # original include guards.
+    programs/test/query_included_headers | grep -x PSA_CRYPTO_PLATFORM_ALT_H
+    programs/test/query_included_headers | grep -x PSA_CRYPTO_STRUCT_ALT_H
+    programs/test/query_included_headers | not grep -x PSA_CRYPTO_PLATFORM_H
+    programs/test/query_included_headers | not grep -x PSA_CRYPTO_STRUCT_H
+}
+
 component_test_m32_o0 () {
     # Build without optimization, so as to use portable C code (in a 32-bit
     # build) and not the i386-specific inline assembly.