diff --git a/CHANGELOG.md b/CHANGELOG.md
index 1c88619..72c651b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -16,6 +16,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 - Random mode modified
 - `filter_color` function modified
 - `filter_projection` function modified
+- `is_same_data` function modified
 - `README.md` updated
 ## [0.6] - 2022-04-13
 ### Added
diff --git a/samila/functions.py b/samila/functions.py
index f7bbe66..c4ef5cc 100644
--- a/samila/functions.py
+++ b/samila/functions.py
@@ -516,6 +516,8 @@ def is_same_data(data1, data2, precision=10**-5):
     :type precision: float
     :return: True if they are the same
     """
+    if len(data1) != len(data2):
+        return False
     is_same = map(lambda x, y: abs(x - y) < precision, data1, data2)
     return all(is_same)
 
diff --git a/test/function_test.py b/test/function_test.py
index bb0dcaf..48ba874 100644
--- a/test/function_test.py
+++ b/test/function_test.py
@@ -9,6 +9,10 @@
 True
 >>> is_same_data([1,1.1,1.2,1.3,1.4],[1,1.11,1.3,1.4,1.5])
 False
+>>> is_same_data(s,[1,1.1,1.2,1.3,1.4,1.5,1.6])
+False
+>>> is_same_data(s,[])
+False
 >>> filter_color("yellow")
 'yellow'
 >>> filter_color((0.2,0.3,0.4))
diff --git a/test/overall_test.py b/test/overall_test.py
index 72221d6..1da3fc9 100644
--- a/test/overall_test.py
+++ b/test/overall_test.py
@@ -208,6 +208,22 @@ False
 >>> del(g)
 >>> del g_.data1
 >>> del(g_)
+>>> g1 = GenerativeImage()
+>>> function1 = eval("lambda x, y:" + g1.function1_str)
+>>> function2 = eval("lambda x, y:" + g1.function2_str)
+>>> g2 = GenerativeImage(function1=function1, function2=function2)
+>>> g1.generate(seed=22)
+>>> g2.generate(seed=22)
+>>> is_same_data(g1.data1, g2.data1)
+True
+>>> is_same_data(g1.data2, g2.data2)
+True
+>>> len(g1.data1) > 0
+True
+>>> len(g1.data2) > 0
+True
+>>> del(g1)
+>>> del(g2)
 >>> os.remove("test.png")
 >>> os.remove("test2.png")
 >>> os.remove("data.json")