diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index a45f73a4232c6c86f3fc6bdb49725cb7fa9dc019..e6915b2a1ae37653a95aef6ccdf0a83ae205ab6d 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -22,6 +22,8 @@ ruby_2.2:
   stage: syntax_22
   tags:
     - ruby
+  only:
+    - master
   script:
     - ruby -v
     - find . -name "*\.rb" -print0 | xargs -I {} -0 -n1 sh -c "ls {}; ruby -c {}"
@@ -31,6 +33,8 @@ ruby_2.3:
   stage: syntax_23
   tags:
     - ruby
+  only:
+    - master
   script:
     - ruby -v
     - find . -name "*\.rb" -print0 | xargs -I {} -0 -n1 sh -c "ls {}; ruby -c {}"
@@ -40,6 +44,8 @@ ruby_2.4:
   stage: syntax_24
   tags:
     - ruby
+  only:
+    - master
   script:
     - ruby -v
     - find . -name "*\.rb" -print0 | xargs -I {} -0 -n1 sh -c "ls {}; ruby -c {}"
@@ -49,6 +55,8 @@ jruby_1.7:
   stage: syntax_j17
   tags:
     - ruby
+  only:
+    - master
   script:
     - ruby -v
     - find . -name "*\.rb" -print0 | xargs -I {} -0 -n1 sh -c "ls {}; ruby -c {}"
@@ -58,6 +66,8 @@ ruby_9.1:
   stage: syntax_j91
   tags:
     - ruby
+  only:
+    - master
   script:
     - ruby -v
     - find . -name "*\.rb" -print0 | xargs -I {} -0 -n1 sh -c "ls {}; ruby -c {}"