diff --git a/scripts/rpm-data/klayout.spec b/scripts/rpm-data/klayout.spec
index 3168ab593..678967a1e 100644
--- a/scripts/rpm-data/klayout.spec
+++ b/scripts/rpm-data/klayout.spec
@@ -36,7 +36,7 @@ AutoReqProv: 	no
 Requires:	ruby >= 2.0.0
 Requires:	python >= 2.7.5
 Requires: qt-x11 >= 4.8.5
-%define buildopt -j2
+%define buildopt -j1
 %endif
 
 %if "%{target_system}" == "centos6"
@@ -45,7 +45,7 @@ Requires: libcurl >= 7.19.7
 Requires: ruby >= 1.8.7
 Requires: python >= 2.6.6
 Requires: qt-x11 >= 4.6.2
-%define buildopt -libcurl -j2
+%define buildopt -libcurl -j1
 %endif
 
 %if "%{target_system}" == "opensuse42_2"
@@ -53,7 +53,7 @@ Requires: qt-x11 >= 4.6.2
 Requires:	ruby2.3 >= 2.3.1
 Requires:	python3 >= 3.4.6
 Requires: libqt4-x11 >= 4.8.6
-%define buildopt -j2
+%define buildopt -j1
 %endif
 
 %if "%{target_system}" == "opensuse42_3"
@@ -61,7 +61,7 @@ Requires: libqt4-x11 >= 4.8.6
 Requires:	ruby2.3 >= 2.3.1
 Requires:	python3 >= 3.4.6
 Requires: libqt4-x11 >= 4.8.6
-%define buildopt -j2
+%define buildopt -j1
 %endif
 
 %description