diff --git a/WDL/Value.py b/WDL/Value.py
index fc2dcdf6..34b66210 100644
--- a/WDL/Value.py
+++ b/WDL/Value.py
@@ -296,7 +296,7 @@ def __str__(self) -> str:
     @property
     def json(self) -> Any:
         ""
-        return [self.value[0].json, self.value[1].json]
+        return {"left": self.value[0].json, "right": self.value[1].json}
 
     @property
     def children(self) -> Iterable[Base]:
@@ -416,11 +416,11 @@ def from_json(type: Type.Base, value: Any) -> Base:
         return String(value)
     if isinstance(type, Type.Array) and isinstance(value, list):
         return Array(type, [from_json(type.item_type, item) for item in value])
-    if isinstance(type, Type.Pair) and isinstance(value, list) and len(value) == 2:
+    if isinstance(type, Type.Pair) and isinstance(value, dict) and set(value) == {"left", "right"}:
         return Pair(
             type.left_type,
             type.right_type,
-            (from_json(type.left_type, value[0]), from_json(type.right_type, value[1])),
+            (from_json(type.left_type, value["left"]), from_json(type.right_type, value["right"])),
         )
     if (
         isinstance(type, Type.Map)
diff --git a/tests/test_0eval.py b/tests/test_0eval.py
index efdcd50b..621388ff 100644
--- a/tests/test_0eval.py
+++ b/tests/test_0eval.py
@@ -453,7 +453,7 @@ def test_json(self):
             (WDL.Type.Map((WDL.Type.String(), WDL.Type.Int())), {"cats": 42, "dogs": 99}),
             (pty, {"name": "Alyssa", "age": 42, "pets": None}),
             (pty, {"name": "Alyssa", "age": 42, "pets": {"cats": 42, "dogs": 99}}),
-            (WDL.Type.Array(WDL.Type.Pair(WDL.Type.String(), WDL.Type.Int())), [["a",0],["b",1]]),
+            (WDL.Type.Array(WDL.Type.Pair(WDL.Type.String(), WDL.Type.Int())), [{"left": "a", "right": 0},{"left": "b", "right": 1}]),
 
             (WDL.Type.Boolean(), 42, WDL.Error.InputError),
             (WDL.Type.Float(), "your president", WDL.Error.InputError),
diff --git a/tests/test_5stdlib.py b/tests/test_5stdlib.py
index e485017f..0251584c 100644
--- a/tests/test_5stdlib.py
+++ b/tests/test_5stdlib.py
@@ -280,7 +280,11 @@ def test_flatten(self):
         """)
         self.assertEqual(outputs["ai"], [1, 2, 3, 1, 21, 22])
         self.assertEqual(outputs["af"], ["/tmp/X.txt", "/tmp/Y.txt", "/tmp/Z.txt"])
-        self.assertEqual(outputs["ap"], [[0.1, "mouse"], [3, "cat"], [15, "dog"]])
+        self.assertEqual(outputs["ap"], [
+            {"left": 0.1, "right": "mouse"},
+            {"left": 3, "right": "cat"},
+            {"left": 15, "right": "dog"}
+        ])
 
     def test_size(self):
         with open(os.path.join(self._dir, "alyssa.txt"), "w") as outfile:
@@ -696,8 +700,19 @@ def test_zip_cross(self):
             }
         }
         """)
-        self.assertEqual(outputs["zipped"], [[1, "a"], [2, "b"], [3, "c"]])
-        self.assertEqual(outputs["crossed"], [[1, "d"], [1, "e"], [2, "d"], [2, "e"], [3, "d"], [3, "e"]])
+        self.assertEqual(outputs["zipped"], [
+            {"left": 1, "right": "a"},
+            {"left": 2, "right": "b"},
+            {"left": 3, "right": "c"}
+        ])
+        self.assertEqual(outputs["crossed"], [
+            {"left": 1, "right": "d"},
+            {"left": 1, "right": "e"},
+            {"left": 2, "right": "d"},
+            {"left": 2, "right": "e"},
+            {"left": 3, "right": "d"},
+            {"left": 3, "right": "e"}
+        ])
 
         outputs = self._test_task(R"""
         version 1.0
diff --git a/tests/test_6workflowrun.py b/tests/test_6workflowrun.py
index 24fc7643..d714e1db 100644
--- a/tests/test_6workflowrun.py
+++ b/tests/test_6workflowrun.py
@@ -176,7 +176,16 @@ def test_scatters(self):
             }
         }
         """, {"m": 4, "n": 2})
-        self.assertEqual(outputs["pairs"], [[0, 0], [0, 1], [1, 0], [1, 1], [2, 0], [2, 1], [3, 0], [3, 1]])
+        self.assertEqual(outputs["pairs"], [
+            {"left": 0, "right": 0},
+            {"left": 0, "right": 1},
+            {"left": 1, "right": 0},
+            {"left": 1, "right": 1},
+            {"left": 2, "right": 0},
+            {"left": 2, "right": 1},
+            {"left": 3, "right": 0},
+            {"left": 3, "right": 1}
+        ])
 
         outputs = self._test_workflow("""
         version 1.0
@@ -213,7 +222,16 @@ def test_scatters(self):
             }
         }
         """, {"m": 4, "n": 2})
-        self.assertEqual(outputs["pairs"], [[0, 0], [0, 1], [1, 0], [1, 1], [2, 0], [2, 1], [3, 0], [3, 1]])
+        self.assertEqual(outputs["pairs"], [
+            {"left": 0, "right": 0},
+            {"left": 0, "right": 1},
+            {"left": 1, "right": 0},
+            {"left": 1, "right": 1},
+            {"left": 2, "right": 0},
+            {"left": 2, "right": 1},
+            {"left": 3, "right": 0},
+            {"left": 3, "right": 1}
+        ])
 
     def test_ifs(self):
         outputs = self._test_workflow("""