diff --git a/README.mkd b/README.mkd
index 588e4fa..6b17c5c 100644
--- a/README.mkd
+++ b/README.mkd
@@ -32,6 +32,18 @@ https://example.com/pathtwo?one=1newval&two=2newval
 https://example.net/a/path?one=1newval&two=2newval
 ```
 
+### Modify Query String Values one at a time
+
+```
+▶ cat urls.txt | qsreplace -u newval
+https://example.com/path?one=newval&two=2
+https://example.com/path?one=1&two=newval
+https://example.com/pathtwo?one=1&two=newval
+https://example.com/pathtwo?one=newval&two=2
+https://example.net/a/path?one=1&two=newval
+https://example.net/a/path?one=newval&two=2
+```
+
 ### Remove Duplicate URL and Parameter Combinations
 
 You can omit the argument to `-a` to only output each combination of URL and query string parameters once:
diff --git a/main.go b/main.go
index 7516383..7e62ad2 100644
--- a/main.go
+++ b/main.go
@@ -12,7 +12,9 @@ import (
 
 func main() {
 	var appendMode bool
+	var uniqueMode bool
 	flag.BoolVar(&appendMode, "a", false, "Append the value instead of replacing it")
+	flag.BoolVar(&uniqueMode, "u", false, "Uniquely modify one parameter at a time")
 	flag.Parse()
 
 	seen := make(map[string]bool)
@@ -31,7 +33,7 @@ func main() {
 		// as part of the key to output only unique requests. To do that, put
 		// them into a slice and then sort it.
 		pp := make([]string, 0)
-		for p, _ := range u.Query() {
+		for p := range u.Query() {
 			pp = append(pp, p)
 		}
 		sort.Strings(pp)
@@ -44,18 +46,39 @@ func main() {
 		}
 		seen[key] = true
 
-		qs := url.Values{}
-		for param, vv := range u.Query() {
-			if appendMode {
-				qs.Set(param, vv[0]+flag.Arg(0))
-			} else {
-				qs.Set(param, flag.Arg(0))
+		if uniqueMode {
+			old_qs := u.Query()
+			for param := range u.Query() {
+				qs := url.Values{}
+				if appendMode {
+					qs.Set(param, old_qs.Get(param)+flag.Arg(0))
+				} else {
+					qs.Set(param, flag.Arg(0))
+				}
+				for p := range u.Query() {
+					if p != param {
+						qs.Set(p, old_qs.Get(p))
+					}
+				}
+
+				u.RawQuery = qs.Encode()
+
+				fmt.Printf("%s\n", u)
+			}
+		} else {
+			qs := url.Values{}
+			for param, vv := range u.Query() {
+				if appendMode {
+					qs.Set(param, vv[0]+flag.Arg(0))
+				} else {
+					qs.Set(param, flag.Arg(0))
+				}
 			}
-		}
 
-		u.RawQuery = qs.Encode()
+			u.RawQuery = qs.Encode()
 
-		fmt.Printf("%s\n", u)
+			fmt.Printf("%s\n", u)
+		}
 
 	}