diff --git a/src/lib.rs b/src/lib.rs
index 3ad9f94..0b3d5af 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -5,9 +5,18 @@ mod lib_test;
 
 fn parse_dice_segments<'a>(cmd: &'a str) -> Vec<regex::Captures<'a>> {
   let regex = Regex::new(r#"(?x)
-    (?P<count>\d+)? # count (optional)
-    d
-    (?P<size>\d+) # dice size
+    (?P<op>[+\-/*])?
+    \s*
+    (?:
+      (?:
+        (?P<count>\d+)? # count (optional)
+        d
+        (?P<size>\d+) # dice size
+        (?:d(?P<drop>\d+))?
+      ) | (?:
+        (?P<mod>\d+)
+      )
+    )
   "#).expect("Failed to compile regex");
 
   regex.captures_iter(cmd).collect()
diff --git a/src/lib_test.rs b/src/lib_test.rs
index 9aa5bd5..9c51ff1 100644
--- a/src/lib_test.rs
+++ b/src/lib_test.rs
@@ -3,13 +3,26 @@ use super::*;
 #[test]
 fn test_roll_dice() {
   let mut results = parse_dice_segments("2d6");
+  
   assert_eq!(results.len(), 1);
   assert_eq!(results[0]["count"], *"2");
   assert_eq!(results[0]["size"], *"6");
   
-  results = parse_dice_segments("2d6+1d20");
+  results = parse_dice_segments("2d6 + 1d20");
   
   assert_eq!(results.len(), 2);
+  assert_eq!(results[1].name("op").map(|i| i.as_str()), Some("+"));
   assert_eq!(results[1].name("count").map(|i| i.as_str()), Some("1"));
   assert_eq!(results[1]["size"], *"20");
+
+  results = parse_dice_segments("4d6d1");
+  
+  assert_eq!(results.len(), 1);
+  assert_eq!(results[0].name("drop").map(|i| i.as_str()), Some("1"));
+
+  results = parse_dice_segments("3d8+8");
+
+  assert_eq!(results.len(), 2);
+  assert_eq!(results[1].name("op").map(|i| i.as_str()), Some("+"));
+  assert_eq!(results[1].name("mod").map(|i| i.as_str()), Some("8"));
 }