diff --git a/tests/scripts/all.sh b/tests/scripts/all.sh
index 943ea88..9ebb120 100755
--- a/tests/scripts/all.sh
+++ b/tests/scripts/all.sh
@@ -3946,9 +3946,24 @@
     shift
     OPTIONS=("$@")
 
+    # clear all of the options so that they can be overridden on the clang commandline
+    for OPT in "${OPTIONS[@]}"; do
+        ./scripts/config.py unset ${OPT}
+    done
+
+    # enter the directory containing the target file & strip the dir from the filename
+    cd $(dirname ${FILE})
+    FILE=$(basename ${FILE})
+
     # The most common issue is unused variables/functions, so ensure -Wunused is set.
     WARNING_FLAGS="-Werror -Wall -Wextra -Wwrite-strings -Wpointer-arith -Wimplicit-fallthrough -Wshadow -Wvla -Wformat=2 -Wno-format-nonliteral -Wshadow -Wasm-operand-widths -Wunused"
 
+    # Extract the command generated by the Makefile to build the target file.
+    # This ensures that we have any include paths, macro definitions, etc
+    # that may be applied by make.
+    # Add -fsyntax-only as we only want a syntax check and don't need to generate a file.
+    MAKE_CMD=$(make -B -n ${FILE} CC=clang CFLAGS="${WARNING_FLAGS} -fsyntax-only" | egrep "^clang")
+
     MAKEFILE=$(mktemp)
     DEPS=""
 
@@ -3973,7 +3988,7 @@
 
         # if valid, add it to the makefile
         if [[ "$INVALID" == "" ]]; then
-            cmd="clang ${CLANG_ARGS} -fsyntax-only ${FILE} -Iinclude -std=c99 $WARNING_FLAGS"
+            cmd="${MAKE_CMD} ${CLANG_ARGS}"
             echo "${TARGET}:" >> ${MAKEFILE}
             echo -e "\t$cmd" >> ${MAKEFILE}
 
@@ -3983,11 +3998,6 @@
 
     echo "all: ${DEPS}" >> ${MAKEFILE}
 
-    # clear all of the options so that they can be overridden on the clang commandline
-    for OPT in "${OPTIONS[@]}"; do
-        ./scripts/config.py unset ${OPT}
-    done
-
     # execute all of the commands via Make (probably in parallel)
     make -s -f ${MAKEFILE} all
 
@@ -4015,7 +4025,7 @@
 
     msg "build: aes.o for all combinations of relevant config options"
 
-    build_test_config_combos library/aes.c validate_aes_config_variations \
+    build_test_config_combos library/aes.o validate_aes_config_variations \
         "MBEDTLS_AES_SETKEY_ENC_ALT" "MBEDTLS_AES_DECRYPT_ALT" \
         "MBEDTLS_AES_ROM_TABLES" "MBEDTLS_AES_ENCRYPT_ALT" "MBEDTLS_AES_SETKEY_DEC_ALT" \
         "MBEDTLS_AES_FEWER_TABLES" "MBEDTLS_PADLOCK_C" "MBEDTLS_AES_USE_HARDWARE_ONLY" \