diff --git a/CHANGELOG.md b/CHANGELOG.md
index 401f6651..fa4faf12 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,12 +1,13 @@
 # Unreleased
-* json: fix TSGenerator on Windows
+* server: `Server(InetSocketAddress(0))` can now be used to bind to any available port.
+* server: make idle restarts quick #96
+* server: initialize `HttpExchange.pathParams` even no route is matched (404), for decorators #82
 * jdbc: between operator introduced with open and closed ranges, also in and notIn
 * jdbc: @NoTransaction can now be used on jobs
 * jdbc: fixed usage of multiple different DataSources when there is an active transaction
+* jdbc: allow calling of `PooledConnection.close()` multiple times #80
+* json: fix TSGenerator on Windows
 * json: TSGenerator will now use more type-safe string template types for java.time classes, e.g. `${number}-${number}-${number}` instead of `string`
-* server: `Server(InetSocketAddress(0))` can now be used to bind to any available port.
-* server: make idle restarts quick #96
-* server: initialize `HttpExchange.pathParams` even no route is matched (404), for decorators #82
 * jackson: serialize enums using their toString() method by default, this fixes `openapi` module usage with `jackson` #88
 * liquibase: do not close jdbc connection if it was passed by user #81
 
diff --git a/jdbc/src/PooledDataSource.kt b/jdbc/src/PooledDataSource.kt
index c523fdf6..6714e6df 100644
--- a/jdbc/src/PooledDataSource.kt
+++ b/jdbc/src/PooledDataSource.kt
@@ -99,12 +99,15 @@ class PooledDataSource(
 
     internal fun checkBySetApplicationName() { applicationName = currentThread().name }
 
-    override fun close() = try {
-      used -= this
-      if (!conn.autoCommit) conn.rollback()
-      available += this
-    } catch (e: SQLException) {
-      log.warn("Failed to return $this: $e")
+    override fun close() {
+      try {
+        if (used.remove(this) != null) {
+          if (!conn.autoCommit) conn.rollback()
+          available += this
+        } else log.warn("Trying to close already returned $this")
+      } catch (e: SQLException) {
+        log.warn("Failed to return $this: $e")
+      }
     }
 
     internal fun reallyClose() = try {
diff --git a/jdbc/test/PooledDataSourceTest.kt b/jdbc/test/PooledDataSourceTest.kt
index d3d94e5f..88fa0cf2 100644
--- a/jdbc/test/PooledDataSourceTest.kt
+++ b/jdbc/test/PooledDataSourceTest.kt
@@ -86,4 +86,21 @@ class PooledDataSourceTest {
     expect(pool.available).toHaveSize(0)
     expect(pool.used.keys).toHaveSize(0)
   }
+
+  @Test fun `close same connection multiple times`() {
+    val conn = pool.connection
+    expect(pool.used.keys).toHaveSize(1)
+    expect(pool.available).toHaveSize(0)
+
+    conn.close()
+    conn.close()
+    conn.close()
+
+    expect(pool.used.keys).toHaveSize(0)
+    expect(pool.available).toHaveSize(1)
+
+    val conn2 = pool.connection
+    expect(pool.connection).notToEqual(conn2)
+    expect(pool.connection).notToEqual(conn2)
+  }
 }