diff --git a/src/Dapper.AOT/Internal/AsyncCommandState.cs b/src/Dapper.AOT/Internal/AsyncCommandState.cs
index 4922de8b..ae3e8086 100644
--- a/src/Dapper.AOT/Internal/AsyncCommandState.cs
+++ b/src/Dapper.AOT/Internal/AsyncCommandState.cs
@@ -123,6 +123,8 @@ public virtual ValueTask DisposeAsync()
 
             if (cmd is not null)
             {
+                // match vanilla's teardown: release caller-supplied parameter objects
+                cmd.Parameters.Clear();
                 if (conn is not null && (_flags & FLAG_CLOSE_CONNECTION) != 0)
                 {
                     // need to close the connection and dispose the command
@@ -178,7 +180,12 @@ public virtual void Dispose()
         {
             var cmd = Command;
             Command = null;
-            cmd?.Dispose();
+            if (cmd is not null)
+            {
+                // match vanilla's teardown: release caller-supplied parameter objects
+                cmd.Parameters.Clear();
+                cmd.Dispose();
+            }
 
             var conn = connection;
             connection = null;
diff --git a/src/Dapper.AOT/Internal/SyncCommandState.cs b/src/Dapper.AOT/Internal/SyncCommandState.cs
index 90674cbb..5ff39a72 100644
--- a/src/Dapper.AOT/Internal/SyncCommandState.cs
+++ b/src/Dapper.AOT/Internal/SyncCommandState.cs
@@ -62,7 +62,12 @@ public void Dispose()
         {
             var cmd = Command;
             Command = null;
-            cmd?.Dispose();
+            if (cmd is not null)
+            {
+                // match vanilla's teardown: release caller-supplied parameter objects
+                cmd.Parameters.Clear();
+                cmd.Dispose();
+            }
 
             var conn = connection;
             connection = null;
diff --git a/src/Dapper.AOT/UnifiedCommand.cs b/src/Dapper.AOT/UnifiedCommand.cs
index f7b69500..6744fbad 100644
--- a/src/Dapper.AOT/UnifiedCommand.cs
+++ b/src/Dapper.AOT/UnifiedCommand.cs
@@ -219,7 +219,14 @@ private DbCommand UnsafeWithCommandForParameters()
 
     internal void Cleanup()
     {
-        dbCommand?.Dispose();
+        if (dbCommand is not null)
+        {
+            // match vanilla Dapper's teardown: a parameter object the caller supplied
+            // (ICustomQueryParameter, DynamicParameters.Add(DbParameter), etc) must not
+            // stay owned by a dead command's collection, or it cannot be reused
+            dbCommand.Parameters.Clear();
+            dbCommand.Dispose();
+        }
 #if NET6_0_OR_GREATER
         batch?.Dispose();
 #endif