diff --git a/ninja.changes b/ninja.changes
index 59759f3..dee4091 100644
--- a/ninja.changes
+++ b/ninja.changes
@@ -1,3 +1,8 @@
+-------------------------------------------------------------------
+Wed Nov  4 16:33:12 UTC 2020 - Ludwig Nussel <lnussel@suse.de>
+
+- LFS fix for 32bit arch builds (gh#ninja-build/ninja#829)
+
 -------------------------------------------------------------------
 Mon Aug 24 20:25:43 UTC 2020 - Dirk Mueller <dmueller@suse.com>
 
diff --git a/ninja.spec b/ninja.spec
index 9e6ca90..50bef3f 100644
--- a/ninja.spec
+++ b/ninja.spec
@@ -40,7 +40,10 @@ building them, quickly.
 
 %build
 export CFLAGS="%{optflags}"
-export CXXFLAGS="%{optflags}"
+%if "%__isa_bits" == "32"
+CFLAGS="$CFLAGS -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64"
+%endif
+export CXXFLAGS="$CFLAGS"
 python3 ./configure.py --bootstrap --verbose
 
 %install