diff --git a/skoolkit/comment.py b/skoolkit/comment.py
index dda49bc3..62f76096 100644
--- a/skoolkit/comment.py
+++ b/skoolkit/comment.py
@@ -132,6 +132,7 @@
 
 class CommentGenerator:
     def __init__(self):
+        self.exp_addr = None
         self.ctx = None
         self.reg = None
 
@@ -436,6 +437,8 @@ def get_comment(self, address, values):
         :param values: The instruction's byte values.
         :return: A comment for the instruction.
         """
+        if address != self.exp_addr:
+            self.ctx = None
         decoder, template, fctx = self.ops[values[0]]
         if decoder is None:
             rv = template
@@ -452,7 +455,8 @@ def get_comment(self, address, values):
         if fctx:
             self.reg, self.ctx = fctx[0].format(*values), fctx[1]
         else:
-            self.reg, self.ctx = None, None
+            self.ctx = None
+        self.exp_addr = (address + len(values)) % 65536
         return comment
 
     def byte_arg(self, template, address, values):
diff --git a/skoolkit/snaskool.py b/skoolkit/snaskool.py
index d81c090c..af1ac373 100644
--- a/skoolkit/snaskool.py
+++ b/skoolkit/snaskool.py
@@ -386,6 +386,10 @@ def _write_registers(self, entry, wrote_desc):
     def _set_instruction_comments(self, block, width, closing, show_text):
         for instruction in block.instructions:
             instruction.comment = [None]
+            if self.comment_gen and not instruction.operation.upper().startswith('DEF'):
+                gcomment = self.comment_gen.get_comment(instruction.address, instruction.bytes)
+            else:
+                gcomment = None
             if block.comment:
                 if block.repeat_comment:
                     instruction.comment[:] = [c[1] for c in block.comment]
@@ -393,8 +397,8 @@ def _set_instruction_comments(self, block, width, closing, show_text):
                     instruction.comment[0] = block.comment.pop(0)[1]
                     while block.comment and block.comment[0][0]:
                         instruction.comment.append(block.comment.pop(0)[1])
-            elif self.comment_gen and not instruction.operation.upper().startswith('DEF'):
-                instruction.comment[0] = self.comment_gen.get_comment(instruction.address, instruction.bytes)
+            elif gcomment:
+                instruction.comment[0] = gcomment
             elif show_text:
                 instruction.comment[0] = self.to_ascii(instruction.bytes)
             elif self.config['Timings']:
diff --git a/tests/test_comment.py b/tests/test_comment.py
index 9a01e6b4..d75bfd65 100644
--- a/tests/test_comment.py
+++ b/tests/test_comment.py
@@ -1231,12 +1231,13 @@ def _sro_opcodes(self, base):
         return opcodes
 
     def _test_conditionals(self, cg, op_hex, reg, *conditionals):
+        addr = 0x8000
         op_v = [int(op_hex[i:i + 2], 16) for i in range(0, len(op_hex), 2)]
         for name in conditionals:
             for cond, exp_comment in CONDITIONALS[name].items():
-                cg.get_comment(0x8000, op_v)
+                cg.get_comment(addr - len(op_v), op_v)
                 cond_v = [int(cond[i:i + 2], 16) for i in range(0, len(cond), 2)]
-                self.assertEqual(cg.get_comment(0x8000, cond_v), exp_comment.format(reg), f'Opcodes: {op_hex} {cond}')
+                self.assertEqual(cg.get_comment(addr, cond_v), exp_comment.format(reg), f'Opcodes: {op_hex} {cond}')
 
     def test_inc(self):
         cg = CommentGenerator()
diff --git a/tests/test_snaskool.py b/tests/test_snaskool.py
index 42e770fa..ea32ea6f 100644
--- a/tests/test_snaskool.py
+++ b/tests/test_snaskool.py
@@ -5323,6 +5323,79 @@ def test_comment_generation(self):
         """
         self._test_write_skool(snapshot, ctl, exp_skool, comments=True)
 
+    def test_comment_generation_with_existing_comments(self):
+        snapshot = [
+            203, 64,                # 00000 BIT 0,B
+            203, 72,                # 00002 BIT 1,B
+            40, 6,                  # 00004 JR Z,12
+            5,                      # 00006 DEC B
+            13,                     # 00007 DEC C
+            32, 2,                  # 00008 JR NZ,12
+            184,                    # 00010 CP B
+            185,                    # 00011 CP C
+            216,                    # 00012 RET C
+        ]
+        ctl = """
+            c 00000
+              00002,2 Test bit 1 of #REGb
+              00007,1 Decrement #REGc
+              00011,1 Compare #REGa with #REGc
+            i 00013
+        """
+        exp_skool = """
+            ; Routine at 0
+            c00000 BIT 0,B       ; Set the zero flag if bit 0 of #REGb is 0
+             00002 BIT 1,B       ; Test bit 1 of #REGb
+             00004 JR Z,12       ; Jump to #R12 if bit 1 of #REGb is reset
+             00006 DEC B         ; #REGb=#REGb-1
+             00007 DEC C         ; Decrement #REGc
+             00008 JR NZ,12      ; Jump to #R12 if #REGc>0
+             00010 CP B          ; Set the zero flag if #REGa=#REGb, or the carry flag if #REGa<#REGb
+             00011 CP C          ; Compare #REGa with #REGc
+            *00012 RET C         ; Return if #REGa<#REGc
+        """
+        self._test_write_skool(snapshot, ctl, exp_skool, comments=True)
+
+    def test_comment_generation_with_interposed_defb_defm_defs_defw(self):
+        snapshot = [
+            203, 69,                # 00000 BIT 0,L
+            0,                      # 00002 DEFB 0
+            40, 11,                 # 00003 JR Z,16
+            37,                     # 00005 DEC H
+            97,                     # 00006 DEFM "a"
+            32, 7,                  # 00007 JR NZ,16
+            187,                    # 00009 CP E
+            0,                      # 00010 DEFS 1
+            48, 3,                  # 00011 JR NC,16
+            146,                    # 00013 SUB D
+            0, 0,                   # 00014 DEFW 0
+            240,                    # 00016 RET P
+        ]
+        ctl = """
+            c 00000
+            B 00002,1
+            T 00006,1
+            S 00010,1
+            W 00014,2
+            i 00017
+        """
+        exp_skool = """
+            ; Routine at 0
+            c00000 BIT 0,L       ; Set the zero flag if bit 0 of #REGl is 0
+             00002 DEFB 0        ;
+             00003 JR Z,16       ; Jump to #R16 if the zero flag is set
+             00005 DEC H         ; #REGh=#REGh-1
+             00006 DEFM "a"      ;
+             00007 JR NZ,16      ; Jump to #R16 if the zero flag is not set
+             00009 CP E          ; Set the zero flag if #REGa=#REGe, or the carry flag if #REGa<#REGe
+             00010 DEFS 1        ;
+             00011 JR NC,16      ; Jump to #R16 if the carry flag is not set
+             00013 SUB D         ; #REGa=#REGa-#REGd
+             00014 DEFW 0        ;
+            *00016 RET P         ; Return if the sign flag is not set (positive)
+        """
+        self._test_write_skool(snapshot, ctl, exp_skool, comments=True)
+
     @patch.object(components, 'SK_CONFIG', None)
     def test_custom_comment_generator(self):
         custom_cg = """