diff --git a/src/interpreter/mod.rs b/src/interpreter/mod.rs
index 46c92281..7f8a2d14 100644
--- a/src/interpreter/mod.rs
+++ b/src/interpreter/mod.rs
@@ -6659,7 +6659,8 @@ impl Interpreter {
                     .await?;
 
                 let args = vec![text_val, pattern_val, replacement_val]; // Note: text, pattern, then replacement
-                crate::stdlib::pattern::native_pattern_replace(args, *_line, *_column)
+                crate::stdlib::pattern::native_pattern_replace(args)
+                    .map_err(|e| RuntimeError::with_kind(e.message, *_line, *_column, e.kind))
             }
 
             Expression::PatternSplit {
@@ -6672,7 +6673,8 @@ impl Interpreter {
                 let pattern_val = self.evaluate_expression(pattern, Rc::clone(&env)).await?;
 
                 let args = vec![text_val, pattern_val];
-                crate::stdlib::pattern::native_pattern_split(args, *_line, *_column)
+                crate::stdlib::pattern::native_pattern_split(args)
+                    .map_err(|e| RuntimeError::with_kind(e.message, *_line, *_column, e.kind))
             }
             Expression::StringSplit {
                 text,
diff --git a/src/stdlib/helpers.rs b/src/stdlib/helpers.rs
index 50709836..11ec42a4 100644
--- a/src/stdlib/helpers.rs
+++ b/src/stdlib/helpers.rs
@@ -434,3 +434,43 @@ pub fn expect_datetime(value: &Value) -> Result<Rc<chrono::NaiveDateTime>, Runti
         )),
     }
 }
+
+/// Extracts a CompiledPattern value from a WFL Value, returning it as a reference-counted CompiledPattern.
+///
+/// Returns an `Rc<CompiledPattern>` clone (incrementing the reference count) if the value
+/// is a Pattern variant.
+///
+/// # Arguments
+///
+/// * `value` - The WFL Value to extract from
+///
+/// # Returns
+///
+/// Returns an `Rc<CompiledPattern>` clone (incrementing the reference count) if the value
+/// is a Pattern variant.
+///
+/// # Errors
+///
+/// Returns `RuntimeError` if the value is not a Pattern, with an error message
+/// indicating the expected type and the actual type received.
+///
+/// # Examples
+///
+/// ```ignore
+/// pub fn pattern_matches_native(args: Vec<Value>) -> Result<Value, RuntimeError> {
+///     check_arg_count("pattern_matches", &args, 2)?;
+///     let compiled_pattern = expect_pattern(&args[1])?;
+///     // Use compiled_pattern.matches(...)
+///     Ok(Value::Bool(true))
+/// }
+/// ```
+pub fn expect_pattern(value: &Value) -> Result<Rc<crate::pattern::CompiledPattern>, RuntimeError> {
+    match value {
+        Value::Pattern(p) => Ok(Rc::clone(p)),
+        _ => Err(RuntimeError::new(
+            format!("Expected a pattern, got {}", value.type_name()),
+            0,
+            0,
+        )),
+    }
+}
diff --git a/src/stdlib/pattern.rs b/src/stdlib/pattern.rs
index 57ce9fd9..82f3549a 100644
--- a/src/stdlib/pattern.rs
+++ b/src/stdlib/pattern.rs
@@ -1,3 +1,4 @@
+use super::helpers::{check_arg_count, expect_pattern, expect_text};
 use crate::interpreter::environment::Environment;
 use crate::interpreter::error::RuntimeError;
 use crate::interpreter::value::Value;
@@ -28,74 +29,24 @@ pub fn register(env: &mut Environment) {
 /// Native function: pattern_matches(text, pattern) -> boolean
 /// Tests if text matches the given compiled pattern
 pub fn pattern_matches_native(args: Vec<Value>) -> Result<Value, RuntimeError> {
-    if args.len() != 2 {
-        return Err(RuntimeError::new(
-            "pattern_matches requires exactly 2 arguments (text, pattern)".to_string(),
-            0,
-            0,
-        ));
-    }
+    check_arg_count("pattern_matches", &args, 2)?;
 
-    let text_str = match &args[0] {
-        Value::Text(s) => s.as_ref(),
-        _ => {
-            return Err(RuntimeError::new(
-                "First argument to pattern_matches must be text".to_string(),
-                0,
-                0,
-            ));
-        }
-    };
+    let text_str = expect_text(&args[0])?;
+    let compiled_pattern = expect_pattern(&args[1])?;
 
-    let compiled_pattern = match &args[1] {
-        Value::Pattern(p) => p,
-        _ => {
-            return Err(RuntimeError::new(
-                "Second argument to pattern_matches must be a compiled pattern".to_string(),
-                0,
-                0,
-            ));
-        }
-    };
-
-    let matches = compiled_pattern.matches(text_str);
+    let matches = compiled_pattern.matches(text_str.as_ref());
     Ok(Value::Bool(matches))
 }
 
 /// Native function: pattern_find(text, pattern) -> object or null
 /// Finds the first match of pattern in text
 pub fn pattern_find_native(args: Vec<Value>) -> Result<Value, RuntimeError> {
-    if args.len() != 2 {
-        return Err(RuntimeError::new(
-            "pattern_find requires exactly 2 arguments (text, pattern)".to_string(),
-            0,
-            0,
-        ));
-    }
+    check_arg_count("pattern_find", &args, 2)?;
 
-    let text_str = match &args[0] {
-        Value::Text(s) => s.as_ref(),
-        _ => {
-            return Err(RuntimeError::new(
-                "First argument to pattern_find must be text".to_string(),
-                0,
-                0,
-            ));
-        }
-    };
-
-    let compiled_pattern = match &args[1] {
-        Value::Pattern(p) => p,
-        _ => {
-            return Err(RuntimeError::new(
-                "Second argument to pattern_find must be a compiled pattern".to_string(),
-                0,
-                0,
-            ));
-        }
-    };
+    let text_str = expect_text(&args[0])?;
+    let compiled_pattern = expect_pattern(&args[1])?;
 
-    match compiled_pattern.find(text_str) {
+    match compiled_pattern.find(text_str.as_ref()) {
         Some(match_result) => {
             let mut result_map = HashMap::new();
             result_map.insert(
@@ -129,37 +80,12 @@ pub fn pattern_find_native(args: Vec<Value>) -> Result<Value, RuntimeError> {
 /// Native function: pattern_find_all(text, pattern) -> list
 /// Finds all matches of pattern in text
 pub fn pattern_find_all_native(args: Vec<Value>) -> Result<Value, RuntimeError> {
-    if args.len() != 2 {
-        return Err(RuntimeError::new(
-            "pattern_find_all requires exactly 2 arguments (text, pattern)".to_string(),
-            0,
-            0,
-        ));
-    }
+    check_arg_count("pattern_find_all", &args, 2)?;
 
-    let text_str = match &args[0] {
-        Value::Text(s) => s.as_ref(),
-        _ => {
-            return Err(RuntimeError::new(
-                "First argument to pattern_find_all must be text".to_string(),
-                0,
-                0,
-            ));
-        }
-    };
-
-    let compiled_pattern = match &args[1] {
-        Value::Pattern(p) => p,
-        _ => {
-            return Err(RuntimeError::new(
-                "Second argument to pattern_find_all must be a compiled pattern".to_string(),
-                0,
-                0,
-            ));
-        }
-    };
+    let text_str = expect_text(&args[0])?;
+    let compiled_pattern = expect_pattern(&args[1])?;
 
-    let matches = compiled_pattern.find_all(text_str);
+    let matches = compiled_pattern.find_all(text_str.as_ref());
     let mut result_list = Vec::new();
 
     for match_result in matches {
@@ -193,98 +119,85 @@ pub fn pattern_find_all_native(args: Vec<Value>) -> Result<Value, RuntimeError>
 }
 
 /// Native function for pattern replacement (called by interpreter)
-pub fn native_pattern_replace(
-    args: Vec<Value>,
-    line: usize,
-    column: usize,
-) -> Result<Value, RuntimeError> {
-    if args.len() != 3 {
-        return Err(RuntimeError::new(
-            "pattern_replace requires exactly 3 arguments".to_string(),
-            line,
-            column,
-        ));
+pub fn native_pattern_replace(args: Vec<Value>) -> Result<Value, RuntimeError> {
+    check_arg_count("pattern_replace", &args, 3)?;
+
+    let text = expect_text(&args[0])?;
+    let pattern = expect_pattern(&args[1])?;
+    let replacement = expect_text(&args[2])?;
+
+    let text_str = text.as_ref();
+    let matches = pattern.find_all(text_str);
+
+    // If no matches, return original text
+    if matches.is_empty() {
+        return Ok(Value::Text(text));
     }
 
-    let text = match &args[0] {
-        Value::Text(t) => t.as_ref(),
-        _ => {
-            return Err(RuntimeError::new(
-                "First argument must be text".to_string(),
-                line,
-                column,
-            ));
-        }
-    };
+    // Build character-to-byte index mapping
+    // This is needed because match indices are character offsets, but string slicing uses byte offsets
+    let char_to_byte: Vec<usize> = text_str
+        .char_indices()
+        .map(|(byte_idx, _)| byte_idx)
+        .collect();
+    let mut char_to_byte = char_to_byte;
+    char_to_byte.push(text_str.len()); // Add final byte position
 
-    let _pattern = match &args[1] {
-        Value::Pattern(p) => p.as_ref(),
-        _ => {
-            return Err(RuntimeError::new(
-                "Second argument must be a pattern".to_string(),
-                line,
-                column,
-            ));
-        }
-    };
+    let mut result = String::with_capacity(text_str.len());
+    let mut last_end_char = 0;
+
+    for m in matches {
+        // Convert character indices to byte indices
+        // Safe access: if index >= len, use length of string (byte offset)
+        let start_byte = if m.start < char_to_byte.len() {
+            char_to_byte[m.start]
+        } else {
+            text_str.len()
+        };
+
+        let last_end_byte = if last_end_char < char_to_byte.len() {
+            char_to_byte[last_end_char]
+        } else {
+            text_str.len()
+        };
 
-    let _replacement = match &args[2] {
-        Value::Text(t) => t.as_ref(),
-        _ => {
-            return Err(RuntimeError::new(
-                "Third argument must be text".to_string(),
-                line,
-                column,
-            ));
+        // Append text between last match and current match
+        if start_byte > last_end_byte {
+            result.push_str(&text_str[last_end_byte..start_byte]);
         }
+
+        // Append replacement
+        result.push_str(replacement.as_ref());
+        last_end_char = m.end;
+    }
+
+    // Append remaining text
+    let last_end_byte = if last_end_char < char_to_byte.len() {
+        char_to_byte[last_end_char]
+    } else {
+        text_str.len()
     };
 
-    // TODO: Update to use new pattern system for replacement
-    Ok(Value::Text(Arc::from(text)))
+    if last_end_byte < text_str.len() {
+        result.push_str(&text_str[last_end_byte..]);
+    }
+
+    Ok(Value::Text(Arc::from(result)))
 }
 
 /// Native function for pattern splitting (called by interpreter)
-pub fn native_pattern_split(
-    args: Vec<Value>,
-    line: usize,
-    column: usize,
-) -> Result<Value, RuntimeError> {
-    if args.len() != 2 {
-        return Err(RuntimeError::new(
-            "pattern_split requires exactly 2 arguments".to_string(),
-            line,
-            column,
-        ));
-    }
-
-    let text = match &args[0] {
-        Value::Text(t) => t.as_ref(),
-        _ => {
-            return Err(RuntimeError::new(
-                "First argument must be text".to_string(),
-                line,
-                column,
-            ));
-        }
-    };
+pub fn native_pattern_split(args: Vec<Value>) -> Result<Value, RuntimeError> {
+    check_arg_count("pattern_split", &args, 2)?;
 
-    let pattern = match &args[1] {
-        Value::Pattern(p) => p,
-        _ => {
-            return Err(RuntimeError::new(
-                "Second argument must be a pattern".to_string(),
-                line,
-                column,
-            ));
-        }
-    };
+    let text = expect_text(&args[0])?;
+    let pattern = expect_pattern(&args[1])?;
 
     // Find all matches of the pattern in the text
-    let matches = pattern.find_all(text);
+    let matches = pattern.find_all(text.as_ref());
 
     // If no matches, return the entire text as a single element
     if matches.is_empty() {
-        let parts = vec![Value::Text(Arc::from(text))];
+        let parts = vec![Value::Text(Arc::clone(&text))];
         return Ok(Value::List(Rc::new(RefCell::new(parts))));
     }
 
diff --git a/src/stdlib/pattern_test.rs b/src/stdlib/pattern_test.rs
index a7a4a9a2..ca05614a 100644
--- a/src/stdlib/pattern_test.rs
+++ b/src/stdlib/pattern_test.rs
@@ -21,7 +21,7 @@ mod tests {
             result
                 .unwrap_err()
                 .to_string()
-                .contains("exactly 2 arguments")
+                .contains("expects 2 arguments")
         );
     }
 
@@ -33,7 +33,7 @@ mod tests {
             result
                 .unwrap_err()
                 .to_string()
-                .contains("exactly 2 arguments")
+                .contains("expects 2 arguments")
         );
     }
 
@@ -45,7 +45,7 @@ mod tests {
             result
                 .unwrap_err()
                 .to_string()
-                .contains("exactly 2 arguments")
+                .contains("expects 2 arguments")
         );
     }
 
@@ -57,6 +57,7 @@ mod tests {
         ];
         let result = pattern_matches_native(args);
         assert!(result.is_err());
-        assert!(result.unwrap_err().to_string().contains("First argument"));
+        // Updated error message from expect_text helper
+        assert!(result.unwrap_err().to_string().contains("Expected text"));
     }
 }