diff --git a/adhocify.c b/adhocify.c
index 12e6869..e170144 100644
--- a/adhocify.c
+++ b/adhocify.c
@@ -227,8 +227,8 @@ bool run(const char *path, const char *eventfile, const char *outfile, uint32_t
 		const char *argv0 = memrchr(path, '/', strlen(path));
 		argv0 = ( argv0 == NULL ) ? path : argv0+1;
 
-		char envvar[19];
-		sprintf(envvar, "adhocifyevent=%"PRIu32, mask); 
+		char envvar[30];
+		snprintf(envvar, 30, "adhocifyevent=%"PRIu32, mask); 
 		putenv(envvar);
 
 		execl(path, argv0, (! noappend) ? eventfile : NULL, NULL);