diff --git a/config.mk b/config.mk
index 6587d3a..9db2d96 100644
--- a/config.mk
+++ b/config.mk
@@ -8,6 +8,6 @@ MANPREFIX = $(PREFIX)/share/man
 #CC = gcc
 #CC = musl-gcc
 LD = $(CC)
-CPPFLAGS = -D_GNU_SOURCE
+CPPFLAGS = -D_GNU_SOURCE -D_FILE_OFFSET_BITS=64
 CFLAGS   = -std=c99 -Wall -Wextra $(CPPFLAGS)
 LDFLAGS  = -s -lcrypt # -static