diff --git a/Makefile b/Makefile
index 13bfa26..21708c2 100644
--- a/Makefile
+++ b/Makefile
@@ -1,4 +1,4 @@
-CPPFLAGS := -D_POSIX_C_SOURCE=200112L $(CPPFLAGS)
+CPPFLAGS := -D_POSIX_C_SOURCE=200112L -D_FILE_OFFSET_BITS=64 $(CPPFLAGS)
 CFLAGS := -std=c99 -O2 -Wall -Wextra -pedantic -Wno-unused-parameter $(CFLAGS)
 O = obj/