diff --git a/lib2geom.changes b/lib2geom.changes
index ba2321a..7c01900 100644
--- a/lib2geom.changes
+++ b/lib2geom.changes
@@ -1,3 +1,9 @@
+-------------------------------------------------------------------
+Wed Aug 23 13:38:04 UTC 2023 - Jan Engelhardt <jengelh@inai.de>
+
+- Add -DNDEBUG to CFLAGS explicitly, since the i586 build depends
+  on it.
+
 -------------------------------------------------------------------
 Thu Jul 27 20:40:32 UTC 2023 - Dirk Stoecker <opensuse@dstoecker.de>
 
diff --git a/lib2geom.spec b/lib2geom.spec
index 5977784..963341b 100644
--- a/lib2geom.spec
+++ b/lib2geom.spec
@@ -70,7 +70,8 @@ needed to develop applications that require %{name}.
 %autosetup -n %{name}-%{short_version} -p1
 
 %build
-%global optflags %optflags -fexcess-precision=fast
+export CFLAGS="%optflags -fexcess-precision=fast -DNDEBUG"
+export CXXFLAGS="$CFLAGS"
 %cmake -Wno-dev \
        -D2GEOM_BUILD_SHARED:BOOL=ON \
        -D2GEOM_TOYS:BOOL=OFF \