diff --git a/check_cc.bat b/check_cc.bat
index 79bbf6b7..77ea2e71 100644
--- a/check_cc.bat
+++ b/check_cc.bat
@@ -19,7 +19,7 @@ if not exist "%MSYS2_PATH%\msys2_shell.cmd" (
     goto finish
 )
 
-echo [INFO] Checking the UCRT64 C compiler...
+echo [INFO] Checking the UCRT64 C compiler and Opus build...
 call "%MSYS2_PATH%\msys2_shell.cmd" -ucrt64 -here -defterm -no-start -c "bash ./check_cc.sh" >> "%PROBE_LOG%" 2>&1
 set "PROBE_RESULT=%ERRORLEVEL%"
 
@@ -28,7 +28,7 @@ set "PROBE_RESULT=%ERRORLEVEL%"
 type "%PROBE_LOG%"
 echo.
 echo [INFO] Log: "%PROBE_LOG%"
-if not "%PROBE_RESULT%"=="0" echo [ERROR] Compiler check failed. See the log above.
+if not "%PROBE_RESULT%"=="0" echo [ERROR] Compiler or Opus check failed. See the log above.
 if /i not "%~1"=="--no-pause" pause
 popd
 exit /b %PROBE_RESULT%
diff --git a/check_cc.sh b/check_cc.sh
index c3e10dde..32d1c86f 100644
--- a/check_cc.sh
+++ b/check_cc.sh
@@ -1,7 +1,7 @@
 #!/bin/bash
 set -uo pipefail
 
-# Проверяем компилятор отдельно от CMake и исходников проекта.
+# Проверяем базовую компиляцию, затем Opus отдельно и через существующую CMake-сборку.
 probe_cc="${UTUN_PROBE_CC:-/ucrt64/bin/cc.exe}"
 printf '[INFO] MSYSTEM=%s\n[INFO] PATH=%s\n[INFO] Compiler=%s\n' "${MSYSTEM:-unset}" "$PATH" "$probe_cc"
 if [ ! -x "$probe_cc" ]; then
@@ -41,3 +41,30 @@ probe_step 'Compile' "$probe_cc" -v -std=c99 -c "$probe_dir/probe.c" -o "$probe_
 probe_step 'Link' "$probe_cc" -v "$probe_dir/probe.o" -o "$probe_dir/probe.exe" || exit $?
 probe_step 'Run' "$probe_dir/probe.exe" || exit $?
 printf '\n[SUCCESS] Compile, link and run completed.\n'
+
+probe_root=$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")" && pwd) || {
+    printf '[ERROR] Cannot locate the repository directory.\n'
+    exit 1
+}
+probe_opus="$probe_root/lib/libopus"
+probe_includes=()
+for probe_include in '' include celt silk silk/float silk/fixed src; do
+    probe_includes+=("-I$probe_opus/$probe_include")
+done
+probe_step 'Compile Opus laplace.c' "$probe_cc" -v -DOPUS_BUILD -DUSE_ALLOCA -DVAR_ARRAYS "${probe_includes[@]}" \
+    -O3 -DNDEBUG -std=gnu99 -MD -MF "$probe_dir/laplace.d" -c "$probe_opus/celt/laplace.c" -o "$probe_dir/laplace.o" || exit $?
+
+probe_build="$probe_root/tools/chatgui/build"
+if [ ! -f "$probe_build/CMakeCache.txt" ]; then
+    printf '[ERROR] Existing ChatGUI build cache not found: %s/CMakeCache.txt\n' "$probe_build"
+    exit 1
+fi
+if ! command -v cmake >/dev/null 2>&1; then
+    printf '[ERROR] cmake is not available in PATH.\n'
+    exit 1
+fi
+probe_step 'CMake cache settings' sed -n -E \
+    '/^CMAKE_(C_COMPILER|C_COMPILER_LAUNCHER|C_FLAGS(_(DEBUG|RELEASE|MINSIZEREL|RELWITHDEBINFO))?|MAKE_PROGRAM|GENERATOR|BUILD_TYPE):/p' \
+    "$probe_build/CMakeCache.txt" || exit $?
+probe_step 'Build Opus with CMake' cmake --build "$probe_build" --target opus_internal --parallel 1 --verbose || exit $?
+printf '\n[SUCCESS] Standalone Opus compilation and CMake Opus build completed.\n'