diff --git a/katrain/core/constants.py b/katrain/core/constants.py
index b48a438..f391d69 100644
--- a/katrain/core/constants.py
+++ b/katrain/core/constants.py
@@ -2,6 +2,7 @@ PROGRAM_NAME = "KaTrain"
 VERSION = "1.7.0"
 HOMEPAGE = "https://github.com/sanderland/katrain"
 CONFIG_MIN_VERSION = "1.7.0"  # keep config files from this version
+ANALYSIS_FORMAT_VERSION = "1.0"
 
 OUTPUT_ERROR = -1
 OUTPUT_KATAGO_STDERR = -0.5
diff --git a/katrain/core/game.py b/katrain/core/game.py
index 92e4079..bb31576 100644
--- a/katrain/core/game.py
+++ b/katrain/core/game.py
@@ -18,6 +18,7 @@ from katrain.core.constants import (
     PLAYER_HUMAN,
     VERSION,
     PROGRAM_NAME,
+    ANALYSIS_FORMAT_VERSION,
 )
 from katrain.core.engine import KataGoEngine
 from katrain.core.game_node import GameNode
@@ -93,7 +94,6 @@ class Game:
     def analyze_all_nodes(self, priority=0, analyze_fast=False, even_if_present=True):
         for node in self.root.nodes_in_tree:
             if even_if_present or not node.analysis_loaded:
-                print(even_if_present, node.analysis_loaded, node.move)
                 node.clear_analysis()
                 node.analyze(self.engines[node.next_player], priority=priority, analyze_fast=analyze_fast)
 
@@ -321,6 +321,8 @@ class Game:
                     x_properties[bw + "R"] = rank_label(player_info.calculated_rank)
         if "+" in str(self.end_result):
             x_properties["RE"] = self.end_result
+        if save_analysis:
+            x_properties["KTV"] = ANALYSIS_FORMAT_VERSION
         self.root.properties = {**root_properties, **{k: [v] for k, v in x_properties.items()}}
         player_names = {bw: re.sub(r"['<>:\"/\\|?*]", "", self.root.get_property("P" + bw, bw)) for bw in "BW"}
         base_game_name = f"katrain_{player_names['B']} vs {player_names['W']}"
diff --git a/katrain/core/game_node.py b/katrain/core/game_node.py
index e6005d7..341f7bb 100644
--- a/katrain/core/game_node.py
+++ b/katrain/core/game_node.py
@@ -7,16 +7,44 @@ from katrain.core.constants import (
     SGF_INTERNAL_COMMENTS_MARKER,
     SGF_SEPARATOR_MARKER,
     PROGRAM_NAME,
+    ANALYSIS_FORMAT_VERSION,
 )
 from katrain.core.lang import i18n
 from katrain.core.sgf_parser import Move, SGFNode
-from katrain.core.utils import evaluation_class, var_to_grid
+from katrain.core.utils import evaluation_class, var_to_grid, pack_floats, unpack_floats
 from katrain.gui.style import INFO_PV_COLOR
 import base64
 import gzip
 import json
 
 
+def analysis_dumps(analysis):
+    analysis = copy.deepcopy(analysis)
+    for movedict in analysis["moves"].values():
+        if "ownership" in movedict:  # per-move ownership rarely used
+            del movedict["ownership"]
+    ownership_data = pack_floats(analysis.pop("ownership"))
+    policy_data = pack_floats(analysis.pop("policy"))
+    main_data = json.dumps(analysis).encode("utf-8")
+    return [
+        base64.standard_b64encode(gzip.compress(data)).decode("utf-8")
+        for data in [ownership_data, policy_data, main_data]
+    ]
+
+
+def analysis_loads(property_array, board_squares, version):
+    if version > ANALYSIS_FORMAT_VERSION:
+        raise ValueError(f"Can not decode analysis data with version {version}, please update {PROGRAM_NAME}")
+    ownership_data, policy_data, main_data, *_ = [
+        gzip.decompress(base64.standard_b64decode(data)) for data in property_array
+    ]
+    return {
+        **json.loads(main_data),
+        "policy": unpack_floats(policy_data, board_squares + 1),
+        "ownership": unpack_floats(ownership_data, board_squares),
+    }
+
+
 class GameNode(SGFNode):
     """Represents a single game node, with one or more moves and placements."""
 
@@ -35,7 +63,9 @@ class GameNode(SGFNode):
     def add_list_property(self, property: str, values: List):
         if property == "KT":
             try:
-                self.analysis = json.loads(gzip.decompress(base64.standard_b64decode(values[0])))
+                szx, szy = self.root.board_size
+                version = self.root.get_property("KTV", "<unknown>")
+                self.analysis = analysis_loads(values, szx * szy, version)
                 self.analysis_loaded = True
             except Exception as e:
                 print(f"Error in loading analysis: {e}")
@@ -61,13 +91,7 @@ class GameNode(SGFNode):
         note = self.note.strip()
         if save_analysis and self.analysis_complete:
             try:
-                analysis = copy.deepcopy(self.analysis)
-                for movedict in analysis["moves"].values():
-                    if "ownership" in movedict:
-                        del movedict["ownership"]
-                properties["KT"] = [
-                    base64.standard_b64encode(gzip.compress(json.dumps(analysis).encode("utf-8"))).decode("utf-8")
-                ]
+                properties["KT"] = analysis_dumps(self.analysis)
             except Exception as e:
                 print(f"Error in saving analysis: {e}")
         if self.points_lost and save_comments_class is not None and eval_thresholds is not None:
diff --git a/katrain/core/utils.py b/katrain/core/utils.py
index a8d1e70..044aa92 100644
--- a/katrain/core/utils.py
+++ b/katrain/core/utils.py
@@ -57,9 +57,12 @@ def find_package_resource(path, silent_errors=False):
 
 
 def pack_floats(float_list):
-    return struct.pack('%sf' % len(float_list), *float_list)
+    return struct.pack(f"{len(float_list)}e", *float_list)
 
 
+def unpack_floats(str, num):
+    return struct.unpack(f"{num}e", str)
+
 
 def format_visits(n):
     if n < 1000: