diff --git a/news/single-line-comment.rst b/news/single-line-comment.rst
new file mode 100644
index 0000000..14c0170
--- /dev/null
+++ b/news/single-line-comment.rst
@@ -0,0 +1,23 @@
+**Added:**
+
+* Support single line comment in the macro file.
+
+**Changed:**
+
+* <news item>
+
+**Deprecated:**
+
+* <news item>
+
+**Removed:**
+
+* <news item>
+
+**Fixed:**
+
+* <news item>
+
+**Security:**
+
+* <news item>
diff --git a/src/diffpy/apps/app_runmacro.py b/src/diffpy/apps/app_runmacro.py
index 47330dd..4ac47a7 100644
--- a/src/diffpy/apps/app_runmacro.py
+++ b/src/diffpy/apps/app_runmacro.py
@@ -45,6 +45,9 @@
 RawValue:
     /[^\s]+/
 ;
+
+
+Comment: /#[^\n]*/;
 """
 
 
diff --git a/src/diffpy/apps/pdfadapter.py b/src/diffpy/apps/pdfadapter.py
index 5ea27ac..dc9b850 100644
--- a/src/diffpy/apps/pdfadapter.py
+++ b/src/diffpy/apps/pdfadapter.py
@@ -3,8 +3,6 @@
 from pathlib import Path
 
 import numpy
-from scipy.optimize import least_squares
-
 from diffpy.srfit.fitbase import (
     FitContribution,
     FitRecipe,
@@ -14,6 +12,7 @@
 from diffpy.srfit.pdf import PDFGenerator, PDFParser
 from diffpy.srfit.structure import constrainAsSpaceGroup
 from diffpy.structure.parsers import getParser
+from scipy.optimize import least_squares
 
 
 class PDFAdapter:
diff --git a/tests/helper.py b/tests/helper.py
index b4b1a4f..f557162 100644
--- a/tests/helper.py
+++ b/tests/helper.py
@@ -1,5 +1,4 @@
 import numpy as np
-
 from diffpy.srfit.fitbase import FitContribution, FitRecipe, Profile
 from diffpy.srfit.pdf import PDFGenerator, PDFParser
 from diffpy.srfit.structure import constrainAsSpaceGroup
diff --git a/tests/test_runmacro.py b/tests/test_runmacro.py
index a2545ba..58ea2d0 100644
--- a/tests/test_runmacro.py
+++ b/tests/test_runmacro.py
@@ -162,6 +162,18 @@ def test_meta_model():
             },
             {},
         ),
+        # C10: comments. Expect no error is raised by textx
+        (
+            f"""
+# This is a comment
+load structure G1 from "{_STRUCTURE_PATH}"
+""",
+            {
+                "initialize_structures.structure_paths": _STRUCTURE_PATH,
+                "initialize_structures.names": ["G1"],
+            },
+            {"G1": "structure"},
+        ),
     ],
 )
 def test_command_processor(