diff --git a/iasm/assemble.c b/iasm/assemble.c
index 4756114..490926f 100755
--- a/iasm/assemble.c
+++ b/iasm/assemble.c
@@ -375,7 +375,7 @@ Description : Delimit label, opcode and address fields of assembler line.
             : field   - address of address field pointer (returned)
             : comment - address of comment string (returned)
     Returns : 
-   Comments : The buffer is broken into shorter strings (destroyed).
+   Comments : 'buffer' is destroyed (broken into shorter strings.
  ******************************************************************************/
 static void
 delimfields(char *buffer,
@@ -401,19 +401,25 @@ delimfields(char *buffer,
     if (*chptr != ';' && *chptr != '\n')
     {
         *opcode = chptr;
-        while (!isspace(*chptr))
+        while (!isspace(*chptr) && *chptr != ';' && *chptr != '\n')
             ++chptr;
-        *chptr = '\0';
-        ++chptr;
+        // at end of opcode
+        if (isspace(*chptr) || *chptr == ';' || *chptr == '\n')
+        {
+            *chptr = '\0';
+            ++chptr;
+        }
 
-        while (isspace(*chptr) && *chptr != ';' && *chptr != '\n')
+        while (*chptr != '\0' && isspace(*chptr) && *chptr != ';' && *chptr != '\n')
             ++chptr;
-        if (*chptr != ';' && *chptr != '\n')
+
+        if (*chptr && *chptr != ';' && *chptr != '\n')
         {
             *field = chptr;
             while (!isspace(*chptr) && *chptr != ';' && *chptr != '\n')
                 ++chptr;
             *chptr = '\0';
+            ++chptr;
             if (strlen(*field) == 0)
                 *field = NULL;
         }
diff --git a/iasm/iasm.c b/iasm/iasm.c
index 2cc51df..2e23439 100755
--- a/iasm/iasm.c
+++ b/iasm/iasm.c
@@ -93,6 +93,7 @@ Debug(char *fmt, ...)
     vsprintf(buff, fmt, ap);
     fprintf(stdout, "%s\n", buff);
     va_end(ap);
+    fflush(stdout);
 }
 
 
diff --git a/pymlac/Makefile b/pymlac/Makefile
index e9d1ee7..b7cdf67 100644
--- a/pymlac/Makefile
+++ b/pymlac/Makefile
@@ -18,4 +18,4 @@ lst:	$(TESTS)
 	../iasm/iasm -l $*.lst $<
 
 clean:
-	rm -Rf *.pyc *~ *.out test_*.ptp *.lst test_*.trace _#*#_.ptp
+	rm -Rf *.pyc *~ *.out test_*.ptp *.lst test_*.trace _#ASM#_.*
diff --git a/pymlac/test_CPU.py b/pymlac/test_CPU.py
index 9f30368..c435268 100644
--- a/pymlac/test_CPU.py
+++ b/pymlac/test_CPU.py
@@ -11,6 +11,8 @@ where <filename> is a file of test instructions and
           -h    prints this help and stops
 """
 
+import time
+
 # We implement a small interpreter to test the CPU.  The test code is read in
 # from a file:
 #
@@ -93,7 +95,9 @@ class TestCPU(object):
             fd.write('\tend\n')
 
         # now assemble file
-        os.system('../iasm/iasm -l %s.lst %s.asm' % (self.AsmFilename, self.AsmFilename))
+        #cmd = '../iasm/iasm -l %s.lst %s.asm >xyzzy 2>&1' % (self.AsmFilename, self.AsmFilename)
+        cmd = '../iasm/iasm -l %s.lst %s.asm' % (self.AsmFilename, self.AsmFilename)
+        res = os.system(cmd)
 
         # read the listing file to get assembled opcode (second line)
         with open(self.AsmFilename+'.lst', 'rb') as fd: