diff --git a/src/danfojs-base/shared/errors.ts b/src/danfojs-base/shared/errors.ts
index cdd256d6..a433ab56 100644
--- a/src/danfojs-base/shared/errors.ts
+++ b/src/danfojs-base/shared/errors.ts
@@ -52,7 +52,7 @@ class ErrorThrower {
     }
 
     throwColumnLengthError = (ndframe: NDframe | DataFrame, arrLen: number): void => {
-        const msg = `ParamError: Column data length mismatch. You provided data with length ${arrLen} but Ndframe has column of length ${ndframe.shape[1]}`
+        const msg = `ParamError: Column data length mismatch. You provided data with length ${arrLen} but Ndframe has column of length ${ndframe.shape[0]}`
         throw new Error(msg)
     }
 
diff --git a/src/danfojs-browser/tests/core/frame.test.js b/src/danfojs-browser/tests/core/frame.test.js
index 9df80e54..593c4e13 100644
--- a/src/danfojs-browser/tests/core/frame.test.js
+++ b/src/danfojs-browser/tests/core/frame.test.js
@@ -123,11 +123,11 @@ describe("DataFrame", function () {
       const data = { alpha: [ "A", "B", "C", "D" ], count: [ 1, 2, 3, 4 ], sum: [ 20.3, 30.456, 40.90, 90.1 ] };
       const df = new dfd.DataFrame(data);
 
-      assert.throws(function () {
-        df.addColumn("new_column", new dfd.Series([ "a", "b", "c" ])),
+      assert.throws(
+        () => df.addColumn("new_column", new dfd.Series([ "a", "b", "c" ])),
         Error,
-        'ParamError: Column data length mismatch. You provided data with length 3 but Ndframe has column of length 4';
-      });
+        'ParamError: Column data length mismatch. You provided data with length 3 but Ndframe has column of length 4'
+      );
 
     });
     it("Ensure add column does not mutate parent when not in place", function () {
diff --git a/src/danfojs-browser/tests/core/generic.test.js b/src/danfojs-browser/tests/core/generic.test.js
index 44683e5a..525ca2cb 100644
--- a/src/danfojs-browser/tests/core/generic.test.js
+++ b/src/danfojs-browser/tests/core/generic.test.js
@@ -59,20 +59,20 @@ describe("Generic (NDFrame)", function () {
 
     it("Throws error on duplicate column name", function () {
       let data = [ [ 21, 20, 1 ], [ 20, 25, 3 ] ];
-      assert.throws(() => {
-        new dfd.NDframe({ data, isSeries: false, columns: [ "A", "A", "C" ] }),
+      assert.throws(
+        () => new dfd.NDframe({ data, isSeries: false, columns: [ "A", "A", "C" ] }),
         Error,
-        "ColumnIndexError: Column index must contain unique values";
-      });
+        "ColumnIndexError: Column index must contain unique values"
+      );
     });
 
     it("Throws error on duplicate index", function () {
-      let data = [ [ 21, 20, 1 ], [ 20, 25, 3 ] ];
-      assert.throws(() => {
-        new dfd.NDframe({ data, isSeries: false, index: [ 1, 1, 2 ] }),
+      let data = [ [ 21, 20, 1 ], [ 20, 25, 3 ], [ 19, 30, 5 ] ];
+      assert.throws(
+        () => new dfd.NDframe({ data, isSeries: false, index: [ 1, 1, 2 ] }),
         Error,
-        "IndexError: Row index must contain unique values";
-      });
+        "IndexError: Row index must contain unique values"
+      );
     });
 
     it("Successfully create a 2D Frame when first value is empty", function () {
diff --git a/src/danfojs-node/test/core/frame.test.ts b/src/danfojs-node/test/core/frame.test.ts
index 8ed759bb..933e6366 100644
--- a/src/danfojs-node/test/core/frame.test.ts
+++ b/src/danfojs-node/test/core/frame.test.ts
@@ -128,11 +128,9 @@ describe("DataFrame", function () {
             const data = { alpha: ["A", "B", "C", "D"], val_count: [1, 2, 3, 4], val_sum: [20.3, 30.456, 40.90, 90.1] };
             const df = new DataFrame(data);
 
-            assert.throws(function () {
-                df.addColumn("new_column", new Series(["a", "b", "c"])),
-                    Error,
-                    'ParamError: Column data length mismatch. You provided data with length 3 but Ndframe has column of length 4'
-            })
+            assert.throws(
+                () => df.addColumn("new_column", new Series(["a", "b", "c"])), Error,
+                'ParamError: Column data length mismatch. You provided data with length 3 but Ndframe has column of length 4');
 
         });
         it("Ensure add column does not mutate parent when not in place", function () {
diff --git a/src/danfojs-node/test/core/generic.test.ts b/src/danfojs-node/test/core/generic.test.ts
index a7c390a0..e484067c 100644
--- a/src/danfojs-node/test/core/generic.test.ts
+++ b/src/danfojs-node/test/core/generic.test.ts
@@ -62,20 +62,16 @@ describe("Generic (NDFrame)", function () {
 
         it("Throws error on duplicate column name", function () {
             let data = [[21, 20, 1], [20, 25, 3]];
-            assert.throws(() => {
-                new NDframe({ data, isSeries: false, columns: ["A", "A", "C"] }),
-                    Error,
-                    "ColumnIndexError: Column index must contain unique values"
-            });
+            assert.throws(
+                () => new NDframe({ data, isSeries: false, columns: ["A", "A", "C"] }), Error,
+                "ColumnIndexError: Column index must contain unique values");
         });
 
         it("Throws error on duplicate index", function () {
-            let data = [[21, 20, 1], [20, 25, 3]];
-            assert.throws(() => {
-                new NDframe({ data, isSeries: false, index: [1, 1, 2] }),
-                    Error,
-                    "IndexError: Row index must contain unique values"
-            });
+            let data = [[21, 20, 1], [20, 25, 3], [19, 30, 5]];
+            assert.throws(
+                () => new NDframe({ data, isSeries: false, index: [1, 1, 2] }), Error,
+                "IndexError: Row index must contain unique values");
         });
 
         it("Successfully create a 2D Frame when first value is empty", function () {