diff --git a/src/flag-definitions.h b/src/flag-definitions.h
index d90cf79bc5..d597777825 100644
--- a/src/flag-definitions.h
+++ b/src/flag-definitions.h
@@ -555,8 +555,7 @@ DEFINE_BOOL(wasm_break_on_decoder_error, false,
             "debug break when wasm decoder encounters an error")
 
 DEFINE_BOOL(validate_asm, false, "validate asm.js modules before compiling")
-DEFINE_BOOL(fast_validate_asm, false,
-            "validate asm.js modules before compiling")
+DEFINE_BOOL(fast_validate_asm, true, "validate asm.js modules before compiling")
 DEFINE_BOOL(suppress_asm_messages, false,
             "don't emit asm.js related messages (for golden file testing)")
 DEFINE_BOOL(trace_asm_time, false, "log asm.js timing info to the console")