diff --git a/assertj-core.spec b/assertj-core.spec
index a0ec380..534fbce 100644
--- a/assertj-core.spec
+++ b/assertj-core.spec
@@ -48,7 +48,7 @@ rm -r src/test/java/org/assertj/core/internal/{Paths*.java,paths}
 %pom_remove_dep org.junit:junit-bom:
 
 %build
-%mvn_build -f -- -Dproject.build.sourceEncoding=UTF-8
+%mvn_build -f -- -Dproject.build.sourceEncoding=UTF-8 -P \!java9+
 
 %install
 %mvn_install