diff --git a/contracts/FullCheckpoint.sol b/contracts/FullCheckpoint.sol
index eb0b4d5..2571b1a 100644
--- a/contracts/FullCheckpoint.sol
+++ b/contracts/FullCheckpoint.sol
@@ -360,6 +360,17 @@ contract FullCheckpoint {
     function getHeader(
         bytes32 blockHash
     ) public view returns (HeaderInfo memory) {
+        if (headerTree[blockHash].mix == 0) {
+            return (
+                HeaderInfo({
+                    parentHash: 0,
+                    number: 0,
+                    roundNum: 0,
+                    mainnetNum: -1,
+                    finalized: false
+                })
+            );
+        }
         bool finalized = false;
         if (int64(uint64(headerTree[blockHash].mix)) != -1) {
             finalized = true;
diff --git a/contracts/LiteCheckpoint.sol b/contracts/LiteCheckpoint.sol
index 031a163..0bdecbe 100644
--- a/contracts/LiteCheckpoint.sol
+++ b/contracts/LiteCheckpoint.sol
@@ -350,6 +350,18 @@ contract LiteCheckpoint {
     function getHeader(
         bytes32 blockHash
     ) public view returns (HeaderInfo memory) {
+        if (headerTree[blockHash] == 0) {
+            return (
+                HeaderInfo({
+                    parentHash: 0,
+                    number: 0,
+                    roundNum: 0,
+                    mainnetNum: -1,
+                    finalized: false
+                })
+            );
+        }
+
         bool finalized = false;
         if (int64(uint64(headerTree[blockHash])) != -1) {
             finalized = true;
diff --git a/test/FullCheckpoint.js b/test/FullCheckpoint.js
index 85ed47b..d991070 100644
--- a/test/FullCheckpoint.js
+++ b/test/FullCheckpoint.js
@@ -92,6 +92,14 @@ describe("checkpoint", () => {
   });
 
   describe("test checkpoint real block data", () => {
+    it("should check defalut value", async () => {
+      const nonExistentBlock = await checkpoint.getHeader(
+        "0x3a9114857792f2a10b4d04ded4e29cb2371535ed749a7686aa2e9885c6007e25"
+      );
+
+      expect(nonExistentBlock.mainnetNum).to.eq(-1);
+      expect(nonExistentBlock.finalized).to.eq(false);
+    });
     it("should verify roots", async () => {
       const genesisHash = blockToHash(genesis);
       const roots = await checkpoint.getRoots(genesisHash);
diff --git a/test/LiteCheckpoint.js b/test/LiteCheckpoint.js
index d01f25a..ece066e 100644
--- a/test/LiteCheckpoint.js
+++ b/test/LiteCheckpoint.js
@@ -89,6 +89,14 @@ describe("lite checkpoint", () => {
       await loadFixture(fixture));
   });
   describe("test lite checkpoint real block data", () => {
+    it("should check defalut value", async () => {
+      const nonExistentBlock = await liteCheckpoint.getHeader(
+        "0x3a9114857792f2a10b4d04ded4e29cb2371535ed749a7686aa2e9885c6007e25"
+      );
+
+      expect(nonExistentBlock.mainnetNum).to.eq(-1);
+      expect(nonExistentBlock.finalized).to.eq(false);
+    });
     it("should receive a new header which has only the next and uncommitted", async () => {
       await liteCheckpoint.receiveHeader([block451Encoded]);
       const block2Hash = blockToHash(block451Encoded);