diff --git a/src/parser/org_source.rs b/src/parser/org_source.rs
index 3562944..9789c8e 100644
--- a/src/parser/org_source.rs
+++ b/src/parser/org_source.rs
@@ -50,6 +50,12 @@ impl<'s> OrgSource<'s> {
     pub fn is_at_start_of_line(&self) -> bool {
         self.start == self.start_of_line
     }
+
+    pub fn get_until(&self, other: OrgSource<'s>) -> OrgSource<'s> {
+        assert!(other.start >= self.start);
+        assert!(other.end <= self.end);
+        self.slice(..(other.start - self.start))
+    }
 }
 
 impl<'s> InputTake for OrgSource<'s> {
@@ -118,7 +124,6 @@ where
             .map(|idx| self.start + idx + 1)
             .unwrap_or(self.start_of_line);
 
-        // TODO: calculate updated values for WrappedInput
         OrgSource {
             full_source: self.full_source,
             start: new_start,
diff --git a/src/parser/util.rs b/src/parser/util.rs
index 2306cd5..f70685a 100644
--- a/src/parser/util.rs
+++ b/src/parser/util.rs
@@ -49,26 +49,9 @@ pub fn immediate_in_section<'r, 's, 'x>(context: Context<'r, 's>, section_name:
     false
 }
 
-/// Check if the child string slice is a slice of the parent string slice.
-fn is_slice_of(parent: &str, child: &str) -> bool {
-    let parent_start = parent.as_ptr() as usize;
-    let parent_end = parent_start + parent.len();
-    let child_start = child.as_ptr() as usize;
-    let child_end = child_start + child.len();
-    child_start >= parent_start && child_end <= parent_end
-}
-
 /// Get a slice of the string that was consumed in a parser using the original input to the parser and the remaining input after the parser.
 pub fn get_consumed<'s>(input: OrgSource<'s>, remaining: OrgSource<'s>) -> OrgSource<'s> {
-    // TODO: This should be replaced with new logic now that we are wrapping the input type.
-    let input = Into::<&str>::into(&input);
-    let remaining = Into::<&str>::into(&remaining);
-    assert!(is_slice_of(input, remaining));
-    let source = {
-        let offset = remaining.as_ptr() as usize - input.as_ptr() as usize;
-        &input[..offset]
-    };
-    source.into()
+    input.get_until(remaining)
 }
 
 /// A line containing only whitespace and then a line break