diff --git a/ob-prolog.el b/ob-prolog.el
index 5a3c508..59d93b9 100644
--- a/ob-prolog.el
+++ b/ob-prolog.el
@@ -78,7 +78,7 @@
 
 (defun org-babel-prolog--variable-assignment (pair)
   (format "recorda('%s', %s)"
-          (replace-regexp-in-string "'" "\\'" (car pair))
+          (car pair)
           (org-babel-prolog--elisp-to-pl (cdr pair))))
 
 (defun org-babel-variable-assignments:prolog (params)
@@ -149,10 +149,9 @@ resulting in running just the body through the Prolog process."
 			  tmp-file
 			  (replace-regexp-in-string
 			   "\"" "\\\"" (or goal "halt")))))
-    (write-region (org-babel-chomp body) nil tmp-file nil 'no-message)
-    (with-temp-buffer
-      (call-process-shell-command command nil t)
-      (buffer-string))))
+    (with-temp-file tmp-file
+	(insert (org-babel-chomp body)))
+    (org-babel-eval command "")))
 
 (defun org-babel-prolog-evaluate-session (session goal body)
   "Evaluates the GOAL in the BODY of the prolog block in the
diff --git a/ob-prolog.org b/ob-prolog.org
deleted file mode 100644
index 4f840fc..0000000
--- a/ob-prolog.org
+++ /dev/null
@@ -1,50 +0,0 @@
-#+TITLE: Tests for ob-prolog
-
-
-* Simple tests
-
-  #+NAME: f
-  #+BEGIN_SRC elisp
-    '(1 2 3)
-  #+END_SRC
-
-  #+RESULTS: f
-  | 1 | 2 | 3 |
-
-  #+HEADER: :session *prolog-1*
-  #+HEADER: :system swipl
-  #+HEADER: :var a=f()
-  #+HEADER: :var b="asdf"
-  #+HEADER: :goal main(A, D)
-  #+BEGIN_SRC prolog
-    main(A, B) :- recorded(a, A), recorded(b, C), append([C], A, B).
-  #+END_SRC
-
-  #+RESULTS:
-  : A = [1, 2, 3],
-  : D = [asdf, 1, 2, 3].
-
-  #+HEADER: :session *prolog-1*
-  #+HEADER: :goal other(A)
-  #+BEGIN_SRC prolog
-    other(A) :- A is 3.
-  #+END_SRC
-
-  #+RESULTS:
-  : A = 3.
-
-
-  #+begin_src prolog
-    :- format('Hello, ~a.', org_mode).
-  #+end_src
-
-  #+RESULTS:
-  : Hello, org_mode.
-
-  #+begin_src prolog :session *prolog-1*
-    :- format('Hello, ~a.', org_session).
-  #+end_src
-
-  #+RESULTS:
-  : Hello, org_session.
-  : true.
diff --git a/test/test-ob-prolog.el b/test/test-ob-prolog.el
new file mode 100644
index 0000000..4f062fc
--- /dev/null
+++ b/test/test-ob-prolog.el
@@ -0,0 +1,80 @@
+;;; test-ob-prolog.el --- tests for ob-prolog.el
+
+;; Copyright (c) 2015 Bjarte Johansen
+;; Authors: Bjarte Johansen
+
+;; This file is not part of GNU Emacs.
+
+;; This program is free software; you can redistribute it and/or modify
+;; it under the terms of the GNU General Public License as published by
+;; the Free Software Foundation, either version 3 of the License, or
+;; (at your option) any later version.
+
+;; This program is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;; GNU General Public License for more details.
+
+;; You should have received a copy of the GNU General Public License
+;; along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+;;; Code:
+
+(require 'ert)
+(require 'org-id)
+
+
+(unless (featurep 'ob-prolog)
+  (signal 'missing-test-dependency "Support for Prolog code blocks"))
+
+(defmacro test-ob-prolog/test-src-block (number &rest body)
+  (declare (indent 1))
+  (let ((buf (make-symbol "buf"))
+	(visited-p (make-symbol "visited-p"))
+	(file-pos (make-symbol "file-pos"))
+	(file "test-ob-prolog.org"))
+    `(let ((,visited-p (get-file-buffer ,file))
+	   (,buf (find-file-noselect ,file)))
+       (unwind-protect
+	   (with-current-buffer ,buf
+	     (goto-char (point-min))
+	     (condition-case nil
+		 (progn
+		   (org-show-subtree)
+		   (org-show-block-all))
+	       (error nil))
+	     (dotimes (,(make-symbol "_") ,number)
+	       (org-babel-next-src-block))
+	     (save-restriction ,@body))
+	 (unless ,visited-p
+	   (kill-buffer ,buf))))))
+(def-edebug-spec test-ob-prolog/test-src-block (form body))
+
+(ert-deftest test-ob-prolog/simple-execution ()
+  "Test simple execution of prolog source block."
+  (test-ob-prolog/test-src-block 1
+    (should (string= "Hello, org_mode."
+		     (org-babel-execute-src-block)))))
+
+(ert-deftest test-ob-prolog/goal-execution ()
+  "Test execution of goal argument to prolog source block."
+  (test-ob-prolog/test-src-block 2
+    (should (string= "Hello, world!"
+		     (org-babel-execute-src-block)))))
+
+(ert-deftest test-ob-prolog/simple-running-session ()
+  (test-ob-prolog/test-src-block 3
+    (should (string= "A = 41."
+		     (org-babel-execute-src-block)))))
+
+(ert-deftest test-ob-prolog/simple-running-session ()
+  (test-ob-prolog/test-src-block 4
+    (should (string= "A = 42."
+		     (org-babel-execute-src-block)))))
+
+(ert-deftest test-ob-prolog/simple-running-session ()
+  (test-ob-prolog/test-src-block 6
+    (should (string= "A = [0, 1, 2, 3]."
+		     (org-babel-execute-src-block)))))
+
+;;; test-ob-prolog ends here
diff --git a/test/test-ob-prolog.org b/test/test-ob-prolog.org
new file mode 100644
index 0000000..88b4575
--- /dev/null
+++ b/test/test-ob-prolog.org
@@ -0,0 +1,45 @@
+#+PROPERTY: results silent scalar
+#+TITLE: Tests for ob-prolog
+
+
+* Basic prolog source block
+  #+BEGIN_SRC prolog
+    :- format('Hello, ~a.', org_mode).
+  #+END_SRC
+
+* Source block with goal
+  #+BEGIN_SRC prolog :goal main
+    main :-
+        write('Hello, world!').
+  #+END_SRC
+
+* Simple running session
+  #+HEADER: :session *prolog-1*
+  #+HEADER: :goal fourtyone(A)
+  #+BEGIN_SRC prolog
+    fourtyone(A) :- A is 41.
+  #+END_SRC
+
+* Calling predicate from session
+  #+HEADER :session *prolog-1*
+  #+HEADER :goal answer(A)
+  #+BEGIN_SRC prolog
+    answer(C) :-
+        fourtyone(B),
+        C is B+1.
+  #+END_SRC
+
+
+* Test interaction with other blocks
+  #+NAME: f
+  #+BEGIN_SRC elisp :results vector
+    '(1 2 3)
+  #+END_SRC
+
+  #+HEADER: :var a=f()
+  #+HEADER: :var b=0
+  #+HEADER: :goal main(A)
+  #+HEADER: :session *prolog-1*
+  #+BEGIN_SRC prolog
+    main(B) :- recorded(a, A), recorded(b, C), append([C], A, B).
+  #+END_SRC