diff --git a/src/mm.c b/src/mm.c
index 8779e8e..e57e3b3 100644
--- a/src/mm.c
+++ b/src/mm.c
@@ -26,8 +26,6 @@
 #include <unistd.h> /* getopt(3) */
 #include <sysexits.h> /* EX_IOERR, EX_OK, EX_OSERR, EX_USAGE */
 
-extern int errno;
-
 /* This structure is how open files are tracked. */
 struct Files{
 	size_t a;	/* allocation */