diff --git a/proxy/data.go b/proxy/data.go
index bf184fd..cbe3d86 100644
--- a/proxy/data.go
+++ b/proxy/data.go
@@ -61,27 +61,9 @@ func (o Options) String() string {
 
 func ParseOptions(str string) *Options {
 	o := new(Options)
-	var h, w string
 
 	parts := strings.Split(str, ",")
-
-	// parse size
-	size := strings.SplitN(parts[0], "x", 2)
-	w = size[0]
-	if len(size) > 1 {
-		h = size[1]
-	} else {
-		h = w
-	}
-
-	if w != "" {
-		o.Width, _ = strconv.ParseFloat(w, 64)
-	}
-	if h != "" {
-		o.Height, _ = strconv.ParseFloat(h, 64)
-	}
-
-	for _, part := range parts[1:] {
+	for _, part := range parts {
 		if part == "fit" {
 			o.Fit = true
 			continue
@@ -95,10 +77,35 @@ func ParseOptions(str string) *Options {
 			continue
 		}
 
-		if len(part) > 2 && strings.HasPrefix(part, "r") {
+		if len(part) > 2 && part[:1] == "r" {
 			o.Rotate, _ = strconv.Atoi(part[1:])
 			continue
 		}
+
+		if strings.ContainsRune(part, 'x') {
+			var h, w string
+			size := strings.SplitN(part, "x", 2)
+			w = size[0]
+			if len(size) > 1 {
+				h = size[1]
+			} else {
+				h = w
+			}
+
+			if w != "" {
+				o.Width, _ = strconv.ParseFloat(w, 64)
+			}
+			if h != "" {
+				o.Height, _ = strconv.ParseFloat(h, 64)
+			}
+			continue
+		}
+
+		if size, err := strconv.ParseFloat(part, 64); err == nil {
+			o.Width = size
+			o.Height = size
+			continue
+		}
 	}
 
 	return o
diff --git a/proxy/data_test.go b/proxy/data_test.go
index 8bb69eb..054b147 100644
--- a/proxy/data_test.go
+++ b/proxy/data_test.go
@@ -46,6 +46,7 @@ func TestParseOptions(t *testing.T) {
 		{"", emptyOptions},
 		{"x", emptyOptions},
 		{"0", emptyOptions},
+		{",,,,", emptyOptions},
 
 		// size variations
 		{"1x", &Options{Width: 1}},
@@ -54,12 +55,23 @@ func TestParseOptions(t *testing.T) {
 		{"0.1x0.2", &Options{Width: 0.1, Height: 0.2}},
 
 		// additional flags
-		{",fit", &Options{Fit: true}},
-		{",r90", &Options{Rotate: 90}},
-		{",fv", &Options{FlipVertical: true}},
-		{",fh", &Options{FlipHorizontal: true}},
+		{"fit", &Options{Fit: true}},
+		{"r90", &Options{Rotate: 90}},
+		{"fv", &Options{FlipVertical: true}},
+		{"fh", &Options{FlipHorizontal: true}},
+
+		// duplicate flags (last one wins)
+		{"1x2,3x4", &Options{Width: 3, Height: 4}},
+		{"1x2,3", &Options{Width: 3, Height: 3}},
+		{"1x2,0x3", &Options{Width: 0, Height: 3}},
+		{"1x,x2", &Options{Width: 1, Height: 2}},
+		{"r90,r270", &Options{Rotate: 270}},
+
+		// mix of valid and invalid flags
+		{"FOO,1,BAR,r90,BAZ", &Options{Width: 1, Height: 1, Rotate: 90}},
 
 		{"1x2,fit,r90,fv,fh", &Options{1, 2, true, 90, true, true}},
+		{"r90,fh,1x2,fv,fit", &Options{1, 2, true, 90, true, true}},
 	}
 
 	for i, tt := range tests {
diff --git a/readme.md b/readme.md
index 056e228..8171359 100644
--- a/readme.md
+++ b/readme.md
@@ -24,9 +24,10 @@ imageproxy URLs are of the form `http://localhost/{options}/{remote_url}`.
 
 ### Options ###
 
-Options are specified as a comma delimited list of parameters, the first of
-which always specifies image size.  The format is a superset of [resize.ly's
-options](https://resize.ly/#demo).
+Options are specified as a comma delimited list of parameters, which can be
+supplied in any order.  Duplicate parameters overwrite previous values.  
+
+The format is a superset of [resize.ly's options](https://resize.ly/#demo).
 
 #### Size ####