diff --git a/src/Makefile b/src/Makefile
index 03016e58..095a7e11 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -195,6 +195,7 @@ LDFLAGS += $(LDLIBDIRS)
 ifeq ($(target),linux)
 override arch := $(shell uname -m | sed -e 's/^i[3456789]86$$/i386/')
 DEFS += '-DUPX_CONFIG_H="config_h/linux.h"'
+DEFS += -D_FILE_OFFSET_BITS=64
 LDLIBS += -lmcheck
 ifeq ($(arch),i386)
   CC += -march=i386 -mcpu=i586
diff --git a/src/packer.cpp b/src/packer.cpp
index 485fbb85..2955a33b 100644
--- a/src/packer.cpp
+++ b/src/packer.cpp
@@ -472,7 +472,7 @@ void Packer::handleStub(InputFile *fif, OutputFile *fo, long size)
 
 void Packer::checkOverlay(unsigned overlay)
 {
-    assert((off_t)overlay >= 0);
+    assert((int)overlay >= 0);
     assert((off_t)overlay < file_size);
     if (overlay == 0)
         return;