diff --git a/debug10.py b/debug10.py
new file mode 100644
index 0000000..5695bc7
--- /dev/null
+++ b/debug10.py
@@ -0,0 +1,25 @@
+from tatsu.tool import parse
+
+# Test if constants match the literal backtick content
+grammar = '''
+start = x $;
+x = `hello` ;
+'''
+
+print("Testing if constants consume backticks:")
+try:
+    # This should match the literal string `hello` including backticks
+    ast = parse(grammar, '`hello`')
+    print(f"Result: {repr(ast)}")
+except Exception as e:
+    print(f"Error: {e}")
+
+# Test what the constant should produce
+print("\nTesting constant evaluation:")
+try:
+    ast = parse(grammar, '`hello`')
+    print(f"Result: {repr(ast)}")
+    if hasattr(ast, 'x'):
+        print(f"x = {repr(ast.x)} (type: {type(ast.x)})")
+except Exception as e:
+    print(f"Error: {e}")
\ No newline at end of file
diff --git a/debug2.py b/debug2.py
new file mode 100644
index 0000000..d25155c
--- /dev/null
+++ b/debug2.py
@@ -0,0 +1,32 @@
+from tatsu.tool import parse
+
+# Test what happens with different constant values
+grammars = [
+    '''
+    @@grammar :: constants
+    start = int bool str null 'a' $;
+    int = `42` ;
+    bool = `True` ;
+    str = `Something` ;
+    null = `None` ;
+    ''',
+    '''
+    start = int bool str null 'a' $;
+    int = `42` ;
+    bool = `True` ;
+    str = `Something` ;
+    null = `None` ;
+    '''
+]
+
+for i, grammar in enumerate(grammars):
+    print(f"\nTest {i+1}:")
+    try:
+        ast = parse(grammar, 'a')
+        print(f"Result: {repr(ast)}")
+        if hasattr(ast, '__len__'):
+            print(f"Length: {len(ast)}")
+            for j, item in enumerate(ast):
+                print(f"  [{j}]: {repr(item)} (type: {type(item).__name__})")
+    except Exception as e:
+        print(f"Error: {e}")
\ No newline at end of file
diff --git a/debug3.py b/debug3.py
new file mode 100644
index 0000000..0753934
--- /dev/null
+++ b/debug3.py
@@ -0,0 +1,23 @@
+from tatsu.tool import parse
+
+# Test constants without the special grammar directive
+grammar = '''
+start = int bool str null 'a' $;
+int = `42` ;
+bool = `True` ;
+str = `Something` ;
+null = `None` ;
+'''
+
+print("Testing normal constant usage:")
+ast = parse(grammar, 'a')
+print(f"Result: {repr(ast)}")
+if hasattr(ast, '__len__'):
+    print(f"Length: {len(ast)}")
+    for j, item in enumerate(ast):
+        print(f"  [{j}]: {repr(item)} (type: {type(item).__name__})")
+        
+# Expected: (42, True, 'Something', None, 'a')
+expected = (42, True, 'Something', None, 'a')
+print(f"\nExpected: {repr(expected)}")
+print(f"Match: {ast == expected}")
\ No newline at end of file
diff --git a/debug4.py b/debug4.py
new file mode 100644
index 0000000..aaa9429
--- /dev/null
+++ b/debug4.py
@@ -0,0 +1,16 @@
+from tatsu.tool import parse
+
+# Simple test to see if constants work at all
+grammar = '''
+start = null 'a' $;
+null = `None` ;
+'''
+
+print("Testing simple constant:")
+try:
+    ast = parse(grammar, 'a')
+    print(f"Result: {repr(ast)}")
+except Exception as e:
+    print(f"Error: {e}")
+    import traceback
+    traceback.print_exc()
\ No newline at end of file
diff --git a/debug5.py b/debug5.py
new file mode 100644
index 0000000..e2ce263
--- /dev/null
+++ b/debug5.py
@@ -0,0 +1,16 @@
+from tatsu.tool import parse
+
+# Test if constants work when they should match something
+grammar = '''
+start = null $;
+null = `None` ;
+'''
+
+print("Testing constant that should consume input:")
+try:
+    ast = parse(grammar, 'None')
+    print(f"Result: {repr(ast)}")
+except Exception as e:
+    print(f"Error: {e}")
+    import traceback
+    traceback.print_exc()
\ No newline at end of file
diff --git a/debug6.py b/debug6.py
new file mode 100644
index 0000000..89d9618
--- /dev/null
+++ b/debug6.py
@@ -0,0 +1,17 @@
+from tatsu.tool import parse
+
+# Test the actual construct from the issue
+grammar = '''
+start = value:$ ;
+value = `None` ;
+'''
+
+print("Testing value:`None` construct:")
+try:
+    ast = parse(grammar, '')
+    print(f"Result: {repr(ast)}")
+    print(f"Type of value: {type(ast)}")
+except Exception as e:
+    print(f"Error: {e}")
+    import traceback
+    traceback.print_exc()
\ No newline at end of file
diff --git a/debug7.py b/debug7.py
new file mode 100644
index 0000000..bb6bdd0
--- /dev/null
+++ b/debug7.py
@@ -0,0 +1,28 @@
+from tatsu.tool import parse
+
+# Exact test from constants_test.py
+grammar = '''
+@@grammar :: constants
+start = int bool str null 'a' $;
+
+int = `42` ;
+bool = `True` ;
+str = `Something` ;
+null = `None` ;
+'''
+
+print("Testing exact test case:")
+try:
+    ast = parse(grammar, 'a')
+    print(f"Result: {repr(ast)}")
+    print(f"Length: {len(ast)}")
+    for j, item in enumerate(ast):
+        print(f"  [{j}]: {repr(item)} (type: {type(item).__name__})")
+        
+    expected = (42, True, 'Something', None, 'a')
+    print(f"\nExpected: {repr(expected)}")
+    print(f"Match: {ast == expected}")
+except Exception as e:
+    print(f"Error: {e}")
+    import traceback
+    traceback.print_exc()
\ No newline at end of file
diff --git a/debug8.py b/debug8.py
new file mode 100644
index 0000000..91ea128
--- /dev/null
+++ b/debug8.py
@@ -0,0 +1,27 @@
+from tatsu.tool import parse
+
+# Test WITHOUT the constants directive
+grammar = '''
+start = int bool str null 'a' $;
+
+int = `42` ;
+bool = `True` ;
+str = `Something` ;
+null = `None` ;
+'''
+
+print("Testing WITHOUT @@grammar :: constants:")
+try:
+    ast = parse(grammar, 'a')
+    print(f"Result: {repr(ast)}")
+    print(f"Length: {len(ast)}")
+    for j, item in enumerate(ast):
+        print(f"  [{j}]: {repr(item)} (type: {type(item).__name__})")
+        
+    expected = (42, True, 'Something', None, 'a')
+    print(f"\nExpected: {repr(expected)}")
+    print(f"Match: {ast == expected}")
+except Exception as e:
+    print(f"Error: {e}")
+    import traceback
+    traceback.print_exc()
\ No newline at end of file
diff --git a/debug9.py b/debug9.py
new file mode 100644
index 0000000..2ecb8aa
--- /dev/null
+++ b/debug9.py
@@ -0,0 +1,22 @@
+from tatsu.tool import parse
+
+# Absolutely simplest constant test
+grammar = '''
+start = x $;
+x = `hello` ;
+'''
+
+print("Testing simplest constant:")
+try:
+    ast = parse(grammar, 'world')
+    print(f"Result: {repr(ast)}")
+except Exception as e:
+    print(f"Error: {e}")
+
+# Test what it SHOULD match
+print("\nTesting what it should match:")
+try:
+    ast = parse(grammar, 'hello')
+    print(f"Result: {repr(ast)}")
+except Exception as e:
+    print(f"Error: {e}")
\ No newline at end of file
diff --git a/tatsu/grammars.py b/tatsu/grammars.py
index 64c5e28..d03cd68 100644
--- a/tatsu/grammars.py
+++ b/tatsu/grammars.py
@@ -305,6 +305,15 @@ class Constant(Model):
             text = self.literal
             if '\n' in text:
                 text = trim(text)
+            # Handle special literal values that should not be treated as f-strings
+            stripped = text.strip()
+            if stripped in ('None', 'True', 'False') or stripped.isdigit() or \
+               (stripped.startswith('-') and stripped[1:].isdigit()) or \
+               (stripped.count('.') == 1 and all(part.isdigit() for part in stripped.split('.') if part)):
+                try:
+                    return eval(stripped, {}, {})
+                except:
+                    pass  # Fall back to string treatment if eval fails
             return eval(f'{"f" + repr(text)}', {}, dict(ctx.ast))  # pylint: disable=eval-used
         else:
             return self.literal