diff --git a/Source/cmTargetPropCommandBase.h b/Source/cmTargetPropCommandBase.h
index 6bf7c3c06d..487beb4840 100644
--- a/Source/cmTargetPropCommandBase.h
+++ b/Source/cmTargetPropCommandBase.h
@@ -24,8 +24,8 @@ public:
     NO_FLAGS = 0x0,
     PROCESS_BEFORE = 0x1,
     PROCESS_AFTER = 0x2,
-    PROCESS_SYSTEM = 0x3,
-    PROCESS_REUSE_FROM = 0x4
+    PROCESS_SYSTEM = 0x4,
+    PROCESS_REUSE_FROM = 0x8
   };
 
   bool HandleArguments(std::vector<std::string> const& args,
diff --git a/Tests/RunCMake/target_compile_options/RunCMakeTest.cmake b/Tests/RunCMake/target_compile_options/RunCMakeTest.cmake
index f7267599f7..d7038394be 100644
--- a/Tests/RunCMake/target_compile_options/RunCMakeTest.cmake
+++ b/Tests/RunCMake/target_compile_options/RunCMakeTest.cmake
@@ -1,6 +1,7 @@
 include(RunCMake)
 
 run_cmake(empty_keyword_args)
+run_cmake(bad_keyword)
 
 if (CMAKE_C_COMPILER_ID MATCHES "GNU|LCC|Clang")
   macro(run_cmake_target test subtest target)
diff --git a/Tests/RunCMake/target_compile_options/bad_keyword-result.txt b/Tests/RunCMake/target_compile_options/bad_keyword-result.txt
new file mode 100644
index 0000000000..d00491fd7e
--- /dev/null
+++ b/Tests/RunCMake/target_compile_options/bad_keyword-result.txt
@@ -0,0 +1 @@
+1
diff --git a/Tests/RunCMake/target_compile_options/bad_keyword-stderr.txt b/Tests/RunCMake/target_compile_options/bad_keyword-stderr.txt
new file mode 100644
index 0000000000..e22013e960
--- /dev/null
+++ b/Tests/RunCMake/target_compile_options/bad_keyword-stderr.txt
@@ -0,0 +1,2 @@
+CMake Error at bad_keyword\.cmake:[0-9]+ \(target_compile_options\):
+  target_compile_options called with invalid arguments
diff --git a/Tests/RunCMake/target_compile_options/bad_keyword.cmake b/Tests/RunCMake/target_compile_options/bad_keyword.cmake
new file mode 100644
index 0000000000..b7e6fca259
--- /dev/null
+++ b/Tests/RunCMake/target_compile_options/bad_keyword.cmake
@@ -0,0 +1,5 @@
+add_library(iface INTERFACE)
+
+# SYSTEM is a recognized keyword for the base class used to implement the
+# command. Verify that we don't allow it.
+target_compile_options(iface SYSTEM PRIVATE)