diff --git a/klee.changes b/klee.changes
index 16ef08f..67158d0 100644
--- a/klee.changes
+++ b/klee.changes
@@ -1,3 +1,8 @@
+-------------------------------------------------------------------
+Mon Jul 12 23:35:27 UTC 2019 - Aaron Puchert <aaronpuchert@alice-dsl.net>
+
+- Use -flto=thin instead of -flto=<number> for Clang.
+
 -------------------------------------------------------------------
 Mon Jul  1 23:16:30 UTC 2019 - Aaron Puchert <aaronpuchert@alice-dsl.net>
 
diff --git a/klee.spec b/klee.spec
index bca5760..6b22edb 100644
--- a/klee.spec
+++ b/klee.spec
@@ -81,12 +81,20 @@ sed -i '1s@/usr/bin/env python3*@/usr/bin/python3@' \
 	tools/ktest-tool/ktest-tool
 
 %build
+# Make _lto_cflags compatible with Clang. On some arches, it doesn't work.
+%ifarch x86_64 %{ix86} ppc64le s390x
+%define _lto_cflags "-flto=thin"
+%else
+%define _lto_cflags %{nil}
+%endif
 %define __builder ninja
 # they use -DNDEBUG, but we cannot, hence setting CMAKE_C*_FLAGS
 # SHARED libs do not work at all yet
 %cmake \
 	-DCMAKE_C_COMPILER=clang \
 	-DCMAKE_CXX_COMPILER=clang++ \
+	-DCMAKE_AR=%{_bindir}/llvm-ar \
+	-DCMAKE_RANLIB=%{_bindir}/llvm-ranlib \
 	-DENABLE_DOXYGEN=OFF \
 	-DENABLE_SOLVER_STP=ON \
 	-DENABLE_TCMALLOC=ON \