diff --git a/.travis.yml b/.travis.yml
index c98bd12de..2d82e9649 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -26,6 +26,7 @@ before_install:
     openssl aes-256-cbc -K $encrypted_88322e86f6b6_key -iv $encrypted_88322e86f6b6_iv -in secring.gpg.enc -out secring.gpg -d;
   fi
 - export PATH=${PATH}:./vendor/bundle
+- export SBT_JAVA_OPT=-J-Xss64m
 
 install:
 - rvm use 2.3.8 --install --fuzzy
@@ -43,12 +44,12 @@ before_script:
 
 script:
 - if [ "$SCALAENV" = "jvm" ]; then
-    sbt ++$TRAVIS_SCALA_VERSION validateJVM;
+    sbt ++$TRAVIS_SCALA_VERSION $SBT_JAVA_OPT validateJVM;
   elif [ "$SCALAENV" = "js" ]; then
-    sbt ++$TRAVIS_SCALA_VERSION compile;
-    sbt ++$TRAVIS_SCALA_VERSION validateJS;
+    sbt ++$TRAVIS_SCALA_VERSION $SBT_JAVA_OPT compile;
+    sbt ++$TRAVIS_SCALA_VERSION $SBT_JAVA_OPT validateJS;
   elif [ "$G4SBUILD" = "docs" ]; then
-    sbt ++$TRAVIS_SCALA_VERSION docs/tut;
+    sbt ++$TRAVIS_SCALA_VERSION $SBT_JAVA_OPT docs/tut;
   else
     echo "You might not be invited to the party";
   fi
diff --git a/github4s/shared/src/main/scala/github4s/free/domain/PullRequest.scala b/github4s/shared/src/main/scala/github4s/free/domain/PullRequest.scala
index f4a1440d9..0d2538a29 100644
--- a/github4s/shared/src/main/scala/github4s/free/domain/PullRequest.scala
+++ b/github4s/shared/src/main/scala/github4s/free/domain/PullRequest.scala
@@ -28,6 +28,7 @@ case class PullRequest(
     updated_at: Option[String],
     closed_at: Option[String],
     merged_at: Option[String],
+    merge_commit_sha: Option[String],
     base: Option[PullRequestBase],
     head: Option[PullRequestBase],
     user: Option[User],
diff --git a/github4s/shared/src/test/scala/github4s/utils/FakeResponses.scala b/github4s/shared/src/test/scala/github4s/utils/FakeResponses.scala
index 5571f2d0c..0bc9e448c 100644
--- a/github4s/shared/src/test/scala/github4s/utils/FakeResponses.scala
+++ b/github4s/shared/src/test/scala/github4s/utils/FakeResponses.scala
@@ -887,6 +887,7 @@ trait FakeResponses {
       |  "updated_at": "2011-01-26T19:01:12Z",
       |  "closed_at": "2011-01-26T19:01:12Z",
       |  "merged_at": "2011-01-26T19:01:12Z",
+      |  "merge_commit_sha": "e5bd3914e2e596debea16f433f57875b5b90bcd6",
       |  "head": {
       |    "label": "new-topic",
       |    "ref": "new-topic",
@@ -1274,6 +1275,7 @@ trait FakeResponses {
       |  "updated_at": "2011-01-26T19:01:12Z",
       |  "closed_at": "2011-01-26T19:01:12Z",
       |  "merged_at": "2011-01-26T19:01:12Z",
+      |  "merge_commit_sha": "e5bd3914e2e596debea16f433f57875b5b90bcd6",
       |  "head": {
       |    "label": "new-topic",
       |    "ref": "new-topic",
diff --git a/github4s/shared/src/test/scala/github4s/utils/TestData.scala b/github4s/shared/src/test/scala/github4s/utils/TestData.scala
index 93dddbc47..35b2a60dc 100644
--- a/github4s/shared/src/test/scala/github4s/utils/TestData.scala
+++ b/github4s/shared/src/test/scala/github4s/utils/TestData.scala
@@ -114,6 +114,7 @@ trait TestData extends DummyGithubUrls {
   val validPullRequestFileSha      = "f80f79cafbe3f2ba71311b82e1171e73bd37a470"
   val validPullRequestNumber       = 1
   val validPullRequestReviewNumber = 39318789
+  val validMergeCommitSha          = "e5bd3914e2e596debea16f433f57875b5b90bcd6"
 
   val validHead   = "test-pr-issue"
   val invalidHead = ""
@@ -208,6 +209,7 @@ trait TestData extends DummyGithubUrls {
     updated_at = None,
     closed_at = None,
     merged_at = None,
+    merge_commit_sha = Some(validMergeCommitSha),
     base = None,
     head = None,
     user = None,
@@ -371,7 +373,8 @@ trait TestData extends DummyGithubUrls {
       url = s"https://api.github.com/repos/$validRepoOwner/$validRepoName/commits/$validCommitSha"
     ),
     `protected` = Some(true),
-    protection_url = Some(s"https://api.github.com/repos/$validRepoOwner/$validRepoName/branches/$validBranchName/protection")
+    protection_url = Some(
+      s"https://api.github.com/repos/$validRepoOwner/$validRepoName/branches/$validBranchName/protection")
   )
   val branch = protectedBranch.copy(`protected` = None, protection_url = None)