diff --git a/src/Models/PermissionMember.php b/src/Models/PermissionMember.php
index 95e3aba..59a14e2 100644
--- a/src/Models/PermissionMember.php
+++ b/src/Models/PermissionMember.php
@@ -19,6 +19,16 @@ class PermissionMember extends MorphPivot
     ];
 
     protected $casts = [
+        // member_id is a polymorphic varchar(36) that holds either a UUID
+        // (HasUuids host models) or a stringified bigint (auto-increment
+        // host models, e.g. a default User). Casting to string forces the
+        // value to be bound as a string in every query Eloquent builds for
+        // this pivot (attach / detach / where). Without it a bigint member
+        // key is bound as an INTEGER, and MySQL then coerces the WHOLE
+        // varchar column to DOUBLE to compare — which throws
+        // "Truncated incorrect DOUBLE value: '<uuid>'" (error 1292) the
+        // moment a UUID-keyed member shares the same permission.
+        'member_id' => 'string',
         'context' => 'array',
         'expires_at' => 'datetime',
     ];
diff --git a/src/Models/RoleMember.php b/src/Models/RoleMember.php
index 4187a7d..a72e8e8 100644
--- a/src/Models/RoleMember.php
+++ b/src/Models/RoleMember.php
@@ -20,6 +20,16 @@ class RoleMember extends MorphPivot
     ];
 
     protected $casts = [
+        // member_id is a polymorphic varchar(36) that holds either a UUID
+        // (HasUuids host models) or a stringified bigint (auto-increment
+        // host models, e.g. a default User). Casting to string forces the
+        // value to be bound as a string in every query Eloquent builds for
+        // this pivot (attach / detach / where). Without it a bigint member
+        // key is bound as an INTEGER, and MySQL then coerces the WHOLE
+        // varchar column to DOUBLE to compare — which throws
+        // "Truncated incorrect DOUBLE value: '<uuid>'" (error 1292) the
+        // moment a UUID-keyed member shares the same role.
+        'member_id' => 'string',
         'context' => 'array',
         'expires_at' => 'datetime',
         'created_at' => 'datetime',