diff --git a/devices/qemu/arista-veos.json b/devices/qemu/arista-veos.json
index 8d05a6c..e32bdb9 100644
--- a/devices/qemu/arista-veos.json
+++ b/devices/qemu/arista-veos.json
@@ -25,7 +25,7 @@
             {
                 "filename": "Aboot-veos-2.1.0.iso",
                 "version": "2.1.0",
-                "sha1sum": "ea9dc1989764fc6db1d388b061340743016214a7",
+                "md5sum": "44177f7f9157354f213a1545c65e92ec",
                 "download_url": "https://www.arista.com/en/support/software-download"     
             }
         ],
@@ -33,7 +33,7 @@
             {
                 "filename": "vEOS-lab-4.13.8M.vmdk",
                 "version": "4.13.8M",
-                "sha1sum": "ff50656fe817c420e9f7fbb0c0ee41f1ca52fee2",
+                "md5sum": "a47145b9e6e7a24171c0850f8755535e",
                 "download_url": "https://www.arista.com/en/support/software-download"    
             }
         ]
diff --git a/devices/qemu/hp-vsr1001.json b/devices/qemu/hp-vsr1001.json
index 081d918..2f9acee 100644
--- a/devices/qemu/hp-vsr1001.json
+++ b/devices/qemu/hp-vsr1001.json
@@ -29,7 +29,7 @@
             {
                 "filename": "VSR1000_HP-CMW710-R0204P01-X64.iso",
                 "version": "7.10.R0204P01",
-                "sha1sum": "9ead89601e84aa7dd341869c1d7933a583ab2794",
+                "md5sum": "d0b539f3ba9723ad8c3ed46f6d772627",
                 "download_url": "https://h10145.www1.hp.com/Downloads/DownloadSoftware.aspx?SoftwareReleaseUId=11832&ProductNumber=JG811AAE&lang=en&cc=us&prodSeriesId=5443163&OrderNumber=&PurchaseDate="
             }
         ]
diff --git a/devices/qemu/microcore-linux.json b/devices/qemu/microcore-linux.json
index 3b1969a..ebf04bc 100644
--- a/devices/qemu/microcore-linux.json
+++ b/devices/qemu/microcore-linux.json
@@ -24,14 +24,14 @@
             {
                 "filename": "linux-microcore-3.4.1.img",
                 "version": "3.4.1",
-                "sha1sum": "5f42d71b30bc682e44ccf7340e20ea7ea8967ef5",
+                "md5sum": "fa2ec4b1fffad67d8103c3391bbf9df2",
                 "download_url": "https://sourceforge.net/projects/gns-3/files/Qemu%20Appliances/",     
                 "direct_download_url": "http://downloads.sourceforge.net/project/gns-3/Qemu%20Appliances/linux-microcore-3.4.1.img"            
             },
             {
                 "filename": "linux-microcore-4.0.2-clean.img",
                 "version": "4.0.2",
-                "sha1sum": "0252f2c913519c993b812325bbd553af2d77218a",
+                "md5sum": "e13d0d1c0b3999ae2386bba70417930c",
                 "download_url": "https://sourceforge.net/projects/gns-3/files/Qemu%20Appliances/",             
                 "direct_download_url": "http://downloads.sourceforge.net/project/gns-3/Qemu%20Appliances/linux-microcore-4.0.2-clean.img"
             }
diff --git a/gns3registry/image.py b/gns3registry/image.py
index 30a6c45..4d4e596 100644
--- a/gns3registry/image.py
+++ b/gns3registry/image.py
@@ -28,7 +28,7 @@ class Image:
         :params: path of the image
         """
         self._path = path
-        self._sha1sum = None
+        self._md5sum = None
         self._version = None
 
     @property
@@ -53,20 +53,20 @@ class Image:
         self._version = version
 
     @property
-    def sha1sum(self):
+    def md5sum(self):
         """
         Compute a sha1 hash for file
 
         :returns: hexadecimal sha1
         """
 
-        if self._sha1sum is None:
-            m = hashlib.sha1()
+        if self._md5sum is None:
+            m = hashlib.md5()
             with open(self._path, "rb") as f:
                 while True:
-                    buf = f.read(128)
+                    buf = f.read(4096)
                     if not buf:
                         break
                     m.update(buf)
-            self._sha1sum = m.hexdigest()
-        return self._sha1sum
+            self._md5sum = m.hexdigest()
+        return self._md5sum
diff --git a/gns3registry/registry.py b/gns3registry/registry.py
index b49f549..19ebb0a 100644
--- a/gns3registry/registry.py
+++ b/gns3registry/registry.py
@@ -58,11 +58,11 @@ class Registry:
 
         return configurations
 
-    def download_image(self, sha1sum, images_dir):
+    def download_image(self, md5sum, images_dir):
         for config in self._all_configs():
             for image_type in config.get("images", {}):
                 for file in config["images"].get(image_type, []):
-                    if file["sha1sum"] == sha1sum:
+                    if file["md5sum"] == md5sum:
                         path = os.path.join(images_dir, "QEMU", file["filename"])
 
                         if "direct_download_url" in file:
@@ -107,7 +107,7 @@ class Registry:
                 continue
             for file in images:
                 if isinstance(file, dict):
-                    if file.get("sha1sum", None) == image.sha1sum:
+                    if file.get("md5sum", None) == image.md5sum:
                         image.version = file["version"]
                         config["images"][image_type] = image
                         matched = True
diff --git a/test/test_config.py b/test/test_config.py
index 623373a..a56c5a8 100644
--- a/test/test_config.py
+++ b/test/test_config.py
@@ -146,7 +146,7 @@ def test_add_images_cdrom(empty_config, linux_microcore_img):
         "kernel_image": "",
         "legacy_networking": False,
         "name": "HP VSR1001 7.10.R0204P01",
-        "options": "-nographic",
+        "options": "",
         "process_priority": "normal",
         "qemu_path": "qemu-system-x86_64",
         "ram": 1024,
@@ -160,13 +160,13 @@ def test_add_images_router_two_disk(empty_config):
 
     image = MagicMock()
     image.version = "2.1.0"
-    image.sha1sum = "ea9dc1989764fc6db1d388b061340743016214a7"
+    image.md5sum = "ea9dc1989764fc6db1d388b061340743016214a7"
     image.path = "/a"
     config["images"]["hda_disk_image"] = image
 
     image = MagicMock()
     image.version = "4.13.8M"
-    image.sha1sum = "ff50656fe817c420e9f7fbb0c0ee41f1ca52fee2"
+    image.md5sum = "ff50656fe817c420e9f7fbb0c0ee41f1ca52fee2"
     image.path = "/b"
     config["images"]["hdb_disk_image"] = image
 
@@ -218,7 +218,7 @@ def test_add_images_two_disk_one_missing(empty_config):
 
     image = MagicMock()
     image.version = "2.1.0"
-    image.sha1sum = "ea9dc1989764fc6db1d388b061340743016214a7"
+    image.md5sum = "ea9dc1989764fc6db1d388b061340743016214a7"
     config["images"]["hda_disk_image"] = image
 
     with pytest.raises(ConfigException):