diff --git a/check_cc.sh b/check_cc.sh
index 04c3e8e3..8a908a99 100644
--- a/check_cc.sh
+++ b/check_cc.sh
@@ -20,7 +20,7 @@ printf '[INFO] Temporary directory: %s\n' "$probe_dir"
 probe_step() {
     local step="$1" result
     shift
-    printf '\n[INFO] %s\n[INFO] Command:' "$step"
+    printf '\n[INFO] %s\n[INFO] Directory: %s\n[INFO] Command:' "$step" "$PWD"
     printf ' %q' "$@"
     printf '\n'
     "$@"
@@ -102,6 +102,42 @@ if [ "${MSYSTEM:-}" = UCRT64 ]; then
     }
     probe_cmd=$(cygpath -u "${COMSPEC:-C:/Windows/System32/cmd.exe}") || exit $?
     probe_replay=$(cygpath -w "$probe_dir/replay.cmd") || exit $?
+
+    # CMD сохраняет полный Windows-код завершения cc1; Bash оставляет только младший байт.
+    probe_cc1=$("$probe_cc" -print-prog-name=cc1) || { printf '[ERROR] Cannot locate cc1.\n'; exit 1; }
+    probe_cc1=${probe_cc1%$'\r'}
+    probe_cc1=$(cygpath -u "$probe_cc1") || { printf '[ERROR] Cannot resolve the cc1 path.\n'; exit 1; }
+    probe_cc1_native=$(cygpath -w "$probe_cc1") || { printf '[ERROR] Cannot resolve the native cc1 path.\n'; exit 1; }
+    printf '@echo off\r\n"%s" --version\r\nset "UTUN_CC1_RESULT=%%errorlevel%%"\r\n' "$probe_cc1_native" \
+        > "$probe_dir/cc1.cmd" || { printf '[ERROR] Cannot write the cc1 probe script.\n'; exit 1; }
+    printf 'echo [INFO] cc1 Windows exit code: %%UTUN_CC1_RESULT%%\r\nexit /b %%UTUN_CC1_RESULT%%\r\n' \
+        >> "$probe_dir/cc1.cmd" || { printf '[ERROR] Cannot finish the cc1 probe script.\n'; exit 1; }
+    probe_cc1_script=$(cygpath -w "$probe_dir/cc1.cmd") || { printf '[ERROR] Cannot resolve the cc1 script path.\n'; exit 1; }
+    for probe_cwd in "$probe_root" "$probe_build"; do
+        cd -- "$probe_cwd" || { printf '[ERROR] Cannot open probe directory: %s\n' "$probe_cwd"; exit 1; }
+        MSYS2_ARG_CONV_EXCL='*' probe_step 'Launch cc1 directly' "$probe_cmd" /d /c call "$probe_cc1_script"
+        # При ошибке продолжаем сравнение каталогов и DLL, затем повторяем исходный сбой.
+    done
+    cd -- "$probe_root" || { printf '[ERROR] Cannot open the repository directory.\n'; exit 1; }
+    probe_objdump="${probe_cc%/*}/objdump.exe"
+    "$probe_objdump" -p "$probe_cc1" > "$probe_dir/cc1-imports.txt" || {
+        printf '[ERROR] Cannot inspect cc1 imports.\n'; exit 1;
+    }
+    printf '\n[INFO] cc1 DLL imports:\n'
+    sed -n '/DLL Name:/p' "$probe_dir/cc1-imports.txt" || { printf '[ERROR] Cannot read cc1 imports.\n'; exit 1; }
+    for probe_dll in "$probe_build/"*.dll; do
+        [ -f "$probe_dll" ] || continue
+        probe_system_dll="${probe_cc%/*}/${probe_dll##*/}"
+        [ -f "$probe_system_dll" ] || continue
+        cmp -s "$probe_dll" "$probe_system_dll"
+        probe_result=$?
+        case "$probe_result" in
+            0) printf '[INFO] DLL matches UCRT64: %s\n' "${probe_dll##*/}" ;;
+            1) printf '[WARN] DLL differs from UCRT64: %s\n' "${probe_dll##*/}"
+               probe_step 'DLL hashes' sha256sum "$probe_dll" "$probe_system_dll" || exit $? ;;
+            *) printf '[ERROR] Cannot compare DLL: %s, exit code: %d\n' "$probe_dll" "$probe_result"; exit "$probe_result" ;;
+        esac
+    done
     cd -- "$probe_build" || { printf '[ERROR] Cannot open the ChatGUI build directory.\n'; exit 1; }
     MSYS2_ARG_CONV_EXCL='*' probe_step 'Replay Ninja bands.c command with GCC verbose output' \
         "$probe_cmd" /d /c call "$probe_replay" || exit $?