diff --git a/libmysofa.spec b/libmysofa.spec
index ae94840..c3429c7 100644
--- a/libmysofa.spec
+++ b/libmysofa.spec
@@ -1,3 +1,5 @@
+%global __cmake_in_source_build 1
+
 # Some tests are failing:
 # https://github.com/hoene/libmysofa/issues/129
 %ifarch s390x