diff --git a/Modules/CheckCCompilerFlag.cmake b/Modules/CheckCCompilerFlag.cmake
index 750e4fb..6b9a931 100644
--- a/Modules/CheckCCompilerFlag.cmake
+++ b/Modules/CheckCCompilerFlag.cmake
@@ -50,7 +50,7 @@ macro (CHECK_C_COMPILER_FLAG _FLAG _RESULT)
    CHECK_COMPILER_FLAG_COMMON_PATTERNS(_CheckCCompilerFlag_COMMON_PATTERNS)
    CHECK_C_SOURCE_COMPILES("int main(void) { return 0; }" ${_RESULT}
      # Some compilers do not fail with a bad flag
-     FAIL_REGEX "command line option .* is valid for .* but not for C" # GNU
+     FAIL_REGEX "command line option .* is valid for .* but not for C|clang: warning:" # GNU | clang
      ${_CheckCCompilerFlag_COMMON_PATTERNS}
      )
    foreach(v ${_CheckCCompilerFlag_LOCALE_VARS})
diff --git a/Modules/CheckCXXCompilerFlag.cmake b/Modules/CheckCXXCompilerFlag.cmake
index 71b3fd2..a3d254c 100644
--- a/Modules/CheckCXXCompilerFlag.cmake
+++ b/Modules/CheckCXXCompilerFlag.cmake
@@ -49,7 +49,7 @@ macro (CHECK_CXX_COMPILER_FLAG _FLAG _RESULT)
    CHECK_COMPILER_FLAG_COMMON_PATTERNS(_CheckCXXCompilerFlag_COMMON_PATTERNS)
    CHECK_CXX_SOURCE_COMPILES("int main() { return 0; }" ${_RESULT}
      # Some compilers do not fail with a bad flag
-     FAIL_REGEX "command line option .* is valid for .* but not for C\\\\+\\\\+" # GNU
+     FAIL_REGEX "command line option .* is valid for .* but not for C\\\\+\\\\+|clang: warning:" # GNU | clang
      ${_CheckCXXCompilerFlag_COMMON_PATTERNS}
      )
    foreach(v ${_CheckCXXCompilerFlag_LOCALE_VARS})

diff --git a/Modules/CMakeCheckCompilerFlagCommonPatterns.cmake b/Modules/CMakeCheckCompilerFlagCommonPatterns.cmake
index 3141d60..32dacbd 100644
--- a/Modules/CMakeCheckCompilerFlagCommonPatterns.cmake
+++ b/Modules/CMakeCheckCompilerFlagCommonPatterns.cmake
@@ -23,6 +23,8 @@ macro (CHECK_COMPILER_FLAG_COMMON_PATTERNS _VAR)
    set(${_VAR}
      FAIL_REGEX "[Uu]nrecogni[sz]ed .*option"               # GNU, NAG
      FAIL_REGEX "unknown .*option"                          # Clang
+     FAIL_REGEX "optimization flag .* not supported"        # Clang
+     FAIL_REGEX "argument unused during compilation:"       # Clang
      FAIL_REGEX "ignoring unknown option"                   # MSVC, Intel
      FAIL_REGEX "warning D9002"                             # MSVC, any lang
      FAIL_REGEX "option.*not supported"                     # Intel