diff --git a/pyasm/asm_tests/README.rst b/pyasm/asm_tests/README.rst
index c0e9f16..a7d2f40 100755
--- a/pyasm/asm_tests/README.rst
+++ b/pyasm/asm_tests/README.rst
@@ -14,23 +14,24 @@ Test File Layout
 A test file is just an Imlac assembler source file with special comments that
 define tests to be performed.  For example:
 
-```
-; test file
-        org     0100
-        law     1
-        hlt
-        end
-;! 0100 004001
-;! 0101 000000
-```
+::
+
+    ; test file
+            org     0100
+            law     1
+            hlt
+            end
+    ;! 0100 004001
+    ;! 0101 000000
 
 The special test comments have **';!** in column 1.  Normal comments may also
 exist in the file.  Here the test comments are:
 
-```
-;! 0100 004001
-;! 0101 000000
-```
+::
+
+    ;! 0100 004001
+    ;! 0101 000000
+
 which tells **test_harness** to check that the PTP file generated by the
 assembler does load *004001* at address *0100*, etc.
 
@@ -40,18 +41,18 @@ they appear in the file.
 test_harness Usage
 ==================
 
-```
-Usage: test_harness [ -h ] [ -d <directory> ] [ -p <prefix> ]
+::
 
-Where <prefix> is the test filename prefix of files to test,
-      <directory> is a directory of test files.
-
-If <directory> is specified run tests in that directory.  If not specified
-the test directory is assumed to be './tests'.
-
-If <prefix> is specified, run tests on files in the test subdirectory with
-a filename of <prefix>* .  If <prefix> is not specified all files are tested.
-```
+    Usage: test_harness [ -h ] [ -d <directory> ] [ -p <prefix> ]
+    
+    Where <prefix> is the test filename prefix of files to test,
+          <directory> is a directory of test files.
+    
+    If <directory> is specified run tests in that directory.  If not specified
+    the test directory is assumed to be './tests'.
+    
+    If <prefix> is specified, run tests on files in the test subdirectory with
+    a filename of <prefix>* .  If <prefix> is not specified all files are tested.
 
 The future
 ==========