diff --git a/Modules/CheckCCompilerFlag.cmake b/Modules/CheckCCompilerFlag.cmake
index 2213accee..bc15e9a0b 100644
--- a/Modules/CheckCCompilerFlag.cmake
+++ b/Modules/CheckCCompilerFlag.cmake
@@ -6,6 +6,9 @@
 # sets CMAKE_REQUIRED_DEFINITIONS to <flag>.
 # See help for CheckCSourceCompiles for a listing of variables
 # that can otherwise modify the build.
+# The result only tells that the compiler does not give an error message when
+# it encounters the flag. If the flag has any effect or even a specific one is
+# beyond the scope of this module.
 
 #=============================================================================
 # Copyright 2006-2011 Kitware, Inc.
diff --git a/Modules/CheckCXXCompilerFlag.cmake b/Modules/CheckCXXCompilerFlag.cmake
index 5e8db031c..eee3a701e 100644
--- a/Modules/CheckCXXCompilerFlag.cmake
+++ b/Modules/CheckCXXCompilerFlag.cmake
@@ -6,6 +6,9 @@
 # sets CMAKE_REQUIRED_DEFINITIONS to <flag>.
 # See help for CheckCXXSourceCompiles for a listing of variables
 # that can otherwise modify the build.
+# The result only tells that the compiler does not give an error message when
+# it encounters the flag. If the flag has any effect or even a specific one is
+# beyond the scope of this module.
 
 #=============================================================================
 # Copyright 2006-2010 Kitware, Inc.