diff --git a/tools/7z/patches/7-zip-flags.patch b/tools/7z/patches/7-zip-flags.patch
new file mode 100644
index 0000000..5c684b0
--- /dev/null
+++ b/tools/7z/patches/7-zip-flags.patch
@@ -0,0 +1,20 @@
+--- a/CPP/7zip/7zip_gcc.mak
++++ b/CPP/7zip/7zip_gcc.mak
+@@ -24,7 +24,7 @@ PROGPATH_STATIC = $(O)/$(PROG)s
+ 
+ 
+ ifneq ($(CC), xlc)
+-CFLAGS_WARN_WALL = -Werror -Wall -Wextra
++CFLAGS_WARN_WALL = -Wall -Wextra
+ endif
+ 
+ # for object file
+@@ -50,7 +50,7 @@ endif
+ endif
+ 
+ # CFLAGS_BASE_LIST = -S
+-CFLAGS_BASE = -O2 $(CFLAGS_BASE_LIST) $(CFLAGS_WARN_WALL) $(CFLAGS_WARN) \
++CFLAGS_BASE = $(CFLAGS_BASE_LIST) $(CFLAGS_WARN_WALL) $(CFLAGS_WARN) -D_GNU_SOURCE \
+  $(CFLAGS_DEBUG) -D_REENTRANT -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE \
+  -fPIC
+