diff --git a/src/formatting.rs b/src/formatting.rs
index bf321bc..5d492ab 100644
--- a/src/formatting.rs
+++ b/src/formatting.rs
@@ -52,7 +52,7 @@ impl StrExt for str {
 }
 
 pub fn get_significant_digits(n: &Float) -> usize {
-    let raw_string = n.to_string().replace('.', "");
+    let raw_string = n.to_string().replace(['.', '-'], "");
 
     let mut consecutive_zeros = 0;
     let mut consecutive_nines = 0;
@@ -119,6 +119,11 @@ mod tests {
         );
     }
 
+    #[test]
+    fn minus() {
+        assert_eq!(pretty_eval("-11", MAX_DIGITS).unwrap(), "-11");
+    }
+
     #[test]
     fn basic_get_significant_digits() {
         let many_zeros = eval("14.00643 + 1.00784 * 4 + 35.446 + 15.9994 * 4");