diff --git a/src/components/map/MapSettings.js b/src/components/map/MapSettings.js
index 1f11809..e5526a7 100644
--- a/src/components/map/MapSettings.js
+++ b/src/components/map/MapSettings.js
@@ -64,7 +64,7 @@ function MapSettings({
           <Input
             type="number"
             name="gridX"
-            value={(map && map.gridX) || 0}
+            value={`${(map && map.gridX) || 0}`}
             onChange={(e) =>
               onSettingsChange("gridX", parseInt(e.target.value))
             }
@@ -78,7 +78,7 @@ function MapSettings({
           <Input
             type="number"
             name="gridY"
-            value={(map && map.gridY) || 0}
+            value={`${(map && map.gridY) || 0}`}
             onChange={(e) =>
               onSettingsChange("gridY", parseInt(e.target.value))
             }
diff --git a/src/components/token/TokenSettings.js b/src/components/token/TokenSettings.js
index 92d2f20..e11b9e8 100644
--- a/src/components/token/TokenSettings.js
+++ b/src/components/token/TokenSettings.js
@@ -19,7 +19,7 @@ function TokenSettings({
           <Input
             type="number"
             name="tokenSize"
-            value={(token && token.defaultSize) || 1}
+            value={`${(token && token.defaultSize) || 0}`}
             onChange={(e) =>
               onSettingsChange("defaultSize", parseInt(e.target.value))
             }
diff --git a/src/modals/SelectMapModal.js b/src/modals/SelectMapModal.js
index 3737027..def4c2b 100644
--- a/src/modals/SelectMapModal.js
+++ b/src/modals/SelectMapModal.js
@@ -249,7 +249,15 @@ function SelectMapModal({
       selectedMapId &&
       (!isEmpty(mapSettingChanges) || !isEmpty(mapStateSettingChanges))
     ) {
-      await updateMap(selectedMapId, mapSettingChanges);
+      // Ensure grid values are positive
+      let verifiedChanges = { ...mapSettingChanges };
+      if ("gridX" in verifiedChanges) {
+        verifiedChanges.gridX = verifiedChanges.gridX || 1;
+      }
+      if ("gridY" in verifiedChanges) {
+        verifiedChanges.gridY = verifiedChanges.gridY || 1;
+      }
+      await updateMap(selectedMapId, verifiedChanges);
       await updateMapState(selectedMapId, mapStateSettingChanges);
 
       setMapSettingChanges({});
diff --git a/src/modals/SelectTokensModal.js b/src/modals/SelectTokensModal.js
index d6b3f14..0feea1b 100644
--- a/src/modals/SelectTokensModal.js
+++ b/src/modals/SelectTokensModal.js
@@ -112,7 +112,13 @@ function SelectTokensModal({ isOpen, onRequestClose }) {
 
   async function applyTokenChanges() {
     if (selectedTokenId && !isEmpty(tokenSettingChanges)) {
-      await updateToken(selectedTokenId, tokenSettingChanges);
+      // Ensure size value is positive
+      let verifiedChanges = { ...tokenSettingChanges };
+      if ("defaultSize" in verifiedChanges) {
+        verifiedChanges.defaultSize = verifiedChanges.defaultSize || 1;
+      }
+
+      await updateToken(selectedTokenId, verifiedChanges);
       setTokenSettingChanges({});
     }
   }