--- a/mfbt/Assertions.h
+++ b/mfbt/Assertions.h
@@ -310,16 +310,20 @@ MOZ_CrashPrintf(const char* aFilename, i
  * a printf-style format string, which must be a string literal and between
  * 1 and 4 additional arguments. A regular MOZ_CRASH() is preferred wherever
  * possible, as passing arbitrary strings to printf from a potentially
  * compromised process is not without risk.
  */
 #define MOZ_CRASH_UNSAFE_PRINTF(format, ...) \
    do { \
      static_assert( \
+       MOZ_ARG_COUNT(__VA_ARGS__) > 0, \
+       "Did you forget arguments to MOZ_CRASH_UNSAFE_PRINTF? " \
+       "Or maybe you want MOZ_CRASH instead?"); \
+     static_assert( \
        MOZ_ARG_COUNT(__VA_ARGS__) <= sPrintfMaxArgs, \
        "Only up to 4 additional arguments are allowed!"); \
      static_assert(sizeof(format) <= sPrintfCrashReasonSize, \
        "The supplied format string is too long!"); \
      MOZ_CALL_CRASH_PRINTF("" format, __VA_ARGS__); \
    } while (0)
 
 MOZ_END_EXTERN_C