diff --git a/package.json b/package.json
index 3075eb44cc..c9fcd28f46 100644
--- a/package.json
+++ b/package.json
@@ -55,6 +55,6 @@
     "flow-bin": "0.100.0",
     "mocha": "6.1.4",
     "nyc": "14.1.1",
-    "prettier": "1.17.1"
+    "prettier": "1.18.0"
   }
 }
diff --git a/src/execution/execute.js b/src/execution/execute.js
index 079dd0d441..e9da2a1166 100644
--- a/src/execution/execute.js
+++ b/src/execution/execute.js
@@ -855,9 +855,7 @@ function completeValue(
     );
     if (completed === null) {
       throw new Error(
-        `Cannot return null for non-nullable field ${info.parentType.name}.${
-          info.fieldName
-        }.`,
+        `Cannot return null for non-nullable field ${info.parentType.name}.${info.fieldName}.`,
       );
     }
     return completed;
@@ -934,9 +932,7 @@ function completeListValue(
 ): PromiseOrValue<$ReadOnlyArray<mixed>> {
   invariant(
     isCollection(result),
-    `Expected Iterable, but did not find one for field ${
-      info.parentType.name
-    }.${info.fieldName}.`,
+    `Expected Iterable, but did not find one for field ${info.parentType.name}.${info.fieldName}.`,
   );
 
   // This is specified as a simple map, however we're optimizing the path
diff --git a/src/jsutils/instanceOf.js b/src/jsutils/instanceOf.js
index 2691ec5cc5..1aeee379f9 100644
--- a/src/jsutils/instanceOf.js
+++ b/src/jsutils/instanceOf.js
@@ -18,7 +18,7 @@ declare function instanceOf(
 
 // See: https://expressjs.com/en/advanced/best-practice-performance.html#set-node_env-to-production
 // See: https://webpack.js.org/guides/production/
-export default (process.env.NODE_ENV === 'production'
+export default process.env.NODE_ENV === 'production'
   ? // eslint-disable-next-line no-shadow
     function instanceOf(value: mixed, constructor: mixed) {
       return value instanceof constructor;
@@ -49,4 +49,4 @@ spurious results.`,
         }
       }
       return false;
-    });
+    };
diff --git a/src/utilities/findBreakingChanges.js b/src/utilities/findBreakingChanges.js
index 42e705b1b4..ddbd48e08c 100644
--- a/src/utilities/findBreakingChanges.js
+++ b/src/utilities/findBreakingChanges.js
@@ -269,9 +269,7 @@ function findUnionTypeChanges(
   for (const newPossibleType of possibleTypesDiff.added) {
     schemaChanges.push({
       type: DangerousChangeType.TYPE_ADDED_TO_UNION,
-      description: `${newPossibleType.name} was added to union type ${
-        oldType.name
-      }.`,
+      description: `${newPossibleType.name} was added to union type ${oldType.name}.`,
     });
   }
 
@@ -304,9 +302,7 @@ function findEnumTypeChanges(
   for (const oldValue of valuesDiff.removed) {
     schemaChanges.push({
       type: BreakingChangeType.VALUE_REMOVED_FROM_ENUM,
-      description: `${oldValue.name} was removed from enum type ${
-        oldType.name
-      }.`,
+      description: `${oldValue.name} was removed from enum type ${oldType.name}.`,
     });
   }
 
@@ -389,9 +385,7 @@ function findArgChanges(
   for (const oldArg of argsDiff.removed) {
     schemaChanges.push({
       type: BreakingChangeType.ARG_REMOVED,
-      description: `${oldType.name}.${oldField.name} arg ${
-        oldArg.name
-      } was removed.`,
+      description: `${oldType.name}.${oldField.name} arg ${oldArg.name} was removed.`,
     });
   }
 
diff --git a/yarn.lock b/yarn.lock
index 0aa4e28b27..9ca5519315 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -2141,10 +2141,10 @@ prettier-linter-helpers@^1.0.0:
   dependencies:
     fast-diff "^1.1.2"
 
-prettier@1.17.1:
-  version "1.17.1"
-  resolved "https://registry.yarnpkg.com/prettier/-/prettier-1.17.1.tgz#ed64b4e93e370cb8a25b9ef7fef3e4fd1c0995db"
-  integrity sha512-TzGRNvuUSmPgwivDqkZ9tM/qTGW9hqDKWOE9YHiyQdixlKbv7kvEqsmDPrcHJTKwthU774TQwZXVtaQ/mMsvjg==
+prettier@1.18.0:
+  version "1.18.0"
+  resolved "https://registry.yarnpkg.com/prettier/-/prettier-1.18.0.tgz#d1701ca9b2941864b52f3262b35946d2c9cd88f0"
+  integrity sha512-YsdAD29M0+WY2xXZk3i0PA16olY9qZss+AuODxglXcJ+2ZBwFv+6k5tE8GS8/HKAthaajlS/WqhdgcjumOrPlg==
 
 private@^0.1.6:
   version "0.1.8"