diff --git a/Source/cmUtilitySourceCommand.h b/Source/cmUtilitySourceCommand.h
index e1866efc8..6364d672a 100644
--- a/Source/cmUtilitySourceCommand.h
+++ b/Source/cmUtilitySourceCommand.h
@@ -70,7 +70,13 @@ public:
       "this command specifies its location and name.  The cache entry will "
       "not be set unless the path_to_source and all listed files exist.  It "
       "is assumed that the source tree of the utility will have been built "
-      "before it is needed.";
+      "before it is needed.\n"
+      "When cross compiling CMake will print a warning if a UTILITY_SOURCE() "
+      "command is executed, because in many cases it is used to build an "
+      "executable which is executed later on. This doesn't work when "
+      "cross compiling, since the executable can run only on their target "
+      "platform. So in this case the cache entry has to be adjusted manually "
+      "so it points to an executable which is runnable on the build host.";
     }
 
   /** This command is kept for compatibility with older CMake versions. */