diff --git a/heaptrack.spec b/heaptrack.spec
index 3695941..e99db62 100644
--- a/heaptrack.spec
+++ b/heaptrack.spec
@@ -85,13 +85,12 @@ A Qt5/KF5 based GUI for Heaptrack.
 # Disable building tests, they're not used and post-build-checks trips over it
 sed -i"" '/add_subdirectory(tests)/d' CMakeLists.txt
 
-extra_options=""
 %if "%{?_lib}" == "lib64"
-extra_options="-DLIB_SUFFIX=64"
+_lib_suffix="64"
 %endif
 
 %build
-  %cmake_kf5 -d build -- $extra_options
+  %cmake_kf5 -d build -- -DLIB_SUFFIX="$_lib_suffix"
   %cmake_build
 
 %install