diff --git a/tests/scripts/all.sh b/tests/scripts/all.sh
index 4705fe8..c0e0d30 100755
--- a/tests/scripts/all.sh
+++ b/tests/scripts/all.sh
@@ -120,6 +120,9 @@
 # Treat uninitialised variables as errors.
 set -e -o pipefail -u
 
+# Enable ksh/bash extended file matching patterns
+shopt -s extglob
+
 pre_check_environment () {
     if [ -d library -a -d include -a -d tests ]; then :; else
         echo "Must be run from mbed TLS root" >&2
@@ -294,7 +297,7 @@
               -iname CTestTestfile.cmake -o \
               -iname CMakeCache.txt \) -exec rm {} \+
     # Recover files overwritten by in-tree CMake builds
-    rm -f include/Makefile include/mbedtls/Makefile programs/*/Makefile
+    rm -f include/Makefile include/mbedtls/Makefile programs/!(fuzz)/Makefile
 
     # Remove any artifacts from the component_test_cmake_as_subdirectory test.
     rm -rf programs/test/cmake_subproject/build
@@ -303,7 +306,9 @@
 
     # Restore files that may have been clobbered by the job
     for x in $files_to_back_up; do
-        cp -p "$x$backup_suffix" "$x"
+        if [[ -e "$x$backup_suffix" ]]; then
+            cp -p "$x$backup_suffix" "$x"
+        fi
     done
 }