diff --git a/src/lsp/iolib.lsp b/src/lsp/iolib.lsp
index 696f488b25d559e4a1281095c34247dbd78671f1..421188e608b7bf9651cd783b079386c8f7b40e58 100644
--- a/src/lsp/iolib.lsp
+++ b/src/lsp/iolib.lsp
@@ -51,15 +51,23 @@ Possible keywords are :INDEX, :START, and :END."
 Evaluates FORMs with VAR bound to a string output stream to the string that is
 the value of STRING-FORM.  If STRING-FORM is not given, a new string is used.
 The stream is automatically closed on exit and the string is returned."
-  (if string
-      `(LET* ((,var (MAKE-STRING-OUTPUT-STREAM-FROM-STRING ,string))
-              (,(gensym) ,element-type))
-        ;; We must evaluate element-type if it has been supplied by the user.
-        ;; Even if we ignore the value afterwards.
-         ,@body)
-      `(LET ((,var (MAKE-STRING-OUTPUT-STREAM ,@r)))
-         ,@body
-         (GET-OUTPUT-STREAM-STRING ,var))))
+  (multiple-value-bind (decls body)
+      (find-declarations body)
+    (if string
+        `(let ((,var (make-string-output-stream-from-string ,string)))
+           ,@decls
+           ;; We must evaluate element-type if it has been supplied by the user.
+           ;; Even if we ignore the value afterwards.
+           ,element-type
+           (unwind-protect (progn ,@body)
+             (close ,var)))
+        `(let ((,var (make-string-output-stream ,@r)))
+           ,@decls
+           ,element-type
+           (unwind-protect (progn
+                             ,@body
+                             (get-output-stream-string ,var))
+             (close ,var))))))
 
 (defun read-from-string (string
                          &optional (eof-error-p t) eof-value
diff --git a/src/tests/normal-tests/mixed.lsp b/src/tests/normal-tests/mixed.lsp
index 4552011857acd346a71ee4f77ad18ca4a0a3bdc0..b1e9cd262285cc0327a9b740c1a46882245ac064 100644
--- a/src/tests/normal-tests/mixed.lsp
+++ b/src/tests/normal-tests/mixed.lsp
@@ -374,16 +374,20 @@
   (signals ext:stack-overflow (labels ((f (x) (f (1+ x))))
                                 (f 1))))
 
-;;; Date 2020-04-18
+;;; Date 2020-04-22
 ;;; URL: https://gitlab.com/embeddable-common-lisp/ecl/-/merge_requests/197
+;;; URL: https://gitlab.com/embeddable-common-lisp/ecl/-/issues/576
 ;;; Description:
 ;;;
-;;;     Ensure that with-input-from-string closes the input stream
-;;;     that it creates.
-(test mix.0019.close-with-input-from-string-stream
+;;;     Ensure that with-input-from-string and with-output-to-string
+;;;     close the streams that they provide.
+(test mix.0019.with-string-io-close-streams
   (let (stream-var)
     (with-input-from-string (inner-stream-var "test")
       (setf stream-var inner-stream-var)
       (is (open-stream-p stream-var)))
-    (is (streamp stream-var))
+    (is (not (open-stream-p stream-var)))
+    (with-output-to-string (inner-stream-var)
+      (setf stream-var inner-stream-var)
+      (is (open-stream-p stream-var)))
     (is (not (open-stream-p stream-var)))))