From what I can tell, possibly snprintf has. ifdef snprintf # error: Macro definition of snprintf conflicts with Standard. But VS onwards you should not # define it with _ snprintf( ). examples\ nftSimple\ nftSimple. c( 62) : note: see previous definition of ' s. fatal error C1189: # error: Macro definition of snprintf conflicts with. fatal error C1189: # error: Macro definition of snprintf conflicts with Standa rd Library function declaration ( compiling source file. I have compiled Firefox Trunk using VS RTM and Windows 10 SDK RTM versions. c failed to compile with the following error: 8: 44. Until now, Many libraries & programs used snprintf( ) function by defining it as _ snprintf( ), since _ snprintf( ) was supported. # define snprintf.