diff --git a/bobbin/crates/resolver/src/legacy_upgrade.rs b/bobbin/crates/resolver/src/legacy_upgrade.rs
index d08a459c9..dd15b59e3 100644
--- a/bobbin/crates/resolver/src/legacy_upgrade.rs
+++ b/bobbin/crates/resolver/src/legacy_upgrade.rs
@@ -384,6 +384,7 @@ async fn upgrade_pull(
         mentions: l.mentions,
         references: l.references,
         rounds,
+        versions: vec![],
         source,
         target,
         title: l.title,
diff --git a/lexicons/git/mergeCheck.json b/lexicons/git/mergeCheck.json
index cd0cb42a4..4650e1b6c 100644
--- a/lexicons/git/mergeCheck.json
+++ b/lexicons/git/mergeCheck.json
@@ -21,19 +21,8 @@
               "description": "Target branch to merge into"
             },
             "source": {
-              "type": "object",
-              "required": ["repo", "commit"],
-              "properties": {
-                "repo": {
-                  "type": "string",
-                  "format": "did",
-                  "description": "DID of source git repository"
-                },
-                "commit": {
-                  "type": "string",
-                  "description": "Head commit ID of PR to merge"
-                }
-              }
+              "type": "ref",
+              "ref": "#source"
             }
           }
         }
@@ -78,6 +67,21 @@
         }
       ]
     },
+    "source": {
+      "type": "object",
+      "required": ["repo", "commit"],
+      "properties": {
+        "repo": {
+          "type": "string",
+          "format": "did",
+          "description": "DID of source git repository"
+        },
+        "commit": {
+          "type": "string",
+          "description": "Head commit ID of PR to merge"
+        }
+      }
+    },
     "conflictInfo": {
       "type": "object",
       "required": ["filename", "reason"],
diff --git a/lexicons/git/mergeCommit.json b/lexicons/git/mergeCommit.json
index 4349323d3..779e452e8 100644
--- a/lexicons/git/mergeCommit.json
+++ b/lexicons/git/mergeCommit.json
@@ -12,34 +12,12 @@
           "required": ["target", "source", "style"],
           "properties": {
             "target": {
-              "type": "object",
-              "required": ["repo", "branch"],
-              "properties": {
-                "repo": {
-                  "type": "string",
-                  "format": "did",
-                  "description": "DID of target git repository"
-                },
-                "branch": {
-                  "type": "string",
-                  "description": "Target branch to merge into"
-                }
-              }
+              "type": "ref",
+              "ref": "#target"
             },
             "source": {
-              "type": "object",
-              "required": ["repo", "commit"],
-              "properties": {
-                "repo": {
-                  "type": "string",
-                  "format": "did",
-                  "description": "DID of source git repository"
-                },
-                "commit": {
-                  "type": "string",
-                  "description": "Head commit ID to merge"
-                }
-              }
+              "type": "ref",
+              "ref": "#source"
             },
             "style": {
               "type": "string",
@@ -53,16 +31,51 @@
               ]
             },
             "mergeCommit": {
-              "type": "object",
-              "description": "Merge commit content. Used when merge commit is created.",
-              "properties": {
-                "author": { "type": "ref", "ref": "sh.tangled.git.defs#signature" },
-                "message": { "type": "string", "maxLength": 1000000 }
-              }
+              "type": "ref",
+              "ref": "#mergeCommitContent",
+              "description": "Merge commit content. Used when merge commit is created."
             }
           }
         }
       }
+    },
+    "target": {
+      "type": "object",
+      "required": ["repo", "branch"],
+      "properties": {
+        "repo": {
+          "type": "string",
+          "format": "did",
+          "description": "DID of target git repository"
+        },
+        "branch": {
+          "type": "string",
+          "description": "Target branch to merge into"
+        }
+      }
+    },
+    "source": {
+      "type": "object",
+      "required": ["repo", "commit"],
+      "properties": {
+        "repo": {
+          "type": "string",
+          "format": "did",
+          "description": "DID of source git repository"
+        },
+        "commit": {
+          "type": "string",
+          "description": "Head commit ID to merge"
+        }
+      }
+    },
+    "mergeCommitContent": {
+      "type": "object",
+      "description": "Merge commit content. Used when merge commit is created.",
+      "properties": {
+        "author": { "type": "ref", "ref": "sh.tangled.git.defs#signature" },
+        "message": { "type": "string", "maxLength": 1000000 }
+      }
     }
   }
 }