diff --git a/tools/flags/SkCommandLineFlags.cpp b/tools/flags/SkCommandLineFlags.cpp
index 9b31b65..42e9ebd 100644
--- a/tools/flags/SkCommandLineFlags.cpp
+++ b/tools/flags/SkCommandLineFlags.cpp
@@ -8,7 +8,7 @@
 #include "SkCommandLineFlags.h"
 #include "SkTDArray.h"
 
-DEFINE_string(undefok, "", "Silently ignore unknown flags listed here instead of crashing.");
+DEFINE_bool(undefok, false, "Silently ignore unknown flags instead of crashing.");
 
 bool SkFlagInfo::CreateStringFlag(const char* name, const char* shortName,
                                   SkCommandLineFlags::StringArray* pStrings,
@@ -291,7 +291,7 @@
                 while (stripped.startsWith('-')) {
                     stripped.remove(0, 1);
                 }
-                if (!FLAGS_undefok.contains(stripped.c_str())) {
+                if (!FLAGS_undefok) {
                     SkDebugf("Got unknown flag \"%s\". Exiting.\n", argv[i]);
                     exit(-1);
                 }