diff --git a/CHANGELOG.md b/CHANGELOG.md
index e043ce8..71c03bf 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -10,6 +10,16 @@ adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 ### Changed
  - updated docker image to use go1.12 compiler and build imageproxy as a go module.
 
+ - options are now sorted when converting to string.  This is a breaking change
+   for anyone relying on the option order, and will additionally invalidate
+   most cached values, since the option string is part of the cache key.
+
+   Both the original remote image, as well as any transformations on that image
+   are cached, but only the transformed images will be impacted by this change.
+   This will result in imageproxy having to re-perform the transformations, but
+   should not result in re-fetching the remote image, unless it has already
+   otherwise expired.
+
 ### Removed
  - removed deprecated `whitelist` flag and `Proxy.Whitelist` struct field. Use
    `allowHosts` and `Proxy.AllowHosts` instead.
diff --git a/data.go b/data.go
index 97b59c5..3968825 100644
--- a/data.go
+++ b/data.go
@@ -19,6 +19,7 @@ import (
 	"net/http"
 	"net/url"
 	"regexp"
+	"sort"
 	"strconv"
 	"strings"
 )
@@ -133,6 +134,7 @@ func (o Options) String() string {
 	if o.SmartCrop {
 		opts = append(opts, optSmartCrop)
 	}
+	sort.Strings(opts)
 	return strings.Join(opts, ",")
 }
 
diff --git a/data_test.go b/data_test.go
index 1416613..9e839c7 100644
--- a/data_test.go
+++ b/data_test.go
@@ -33,19 +33,19 @@ func TestOptions_String(t *testing.T) {
 		},
 		{
 			Options{1, 2, true, 90, true, true, 80, "", false, "", 0, 0, 0, 0, false},
-			"1x2,fit,r90,fv,fh,q80",
+			"1x2,fh,fit,fv,q80,r90",
 		},
 		{
 			Options{0.15, 1.3, false, 45, false, false, 95, "c0ffee", false, "png", 0, 0, 0, 0, false},
-			"0.15x1.3,r45,q95,sc0ffee,png",
+			"0.15x1.3,png,q95,r45,sc0ffee",
 		},
 		{
 			Options{0.15, 1.3, false, 45, false, false, 95, "c0ffee", false, "", 100, 200, 0, 0, false},
-			"0.15x1.3,r45,q95,sc0ffee,cx100,cy200",
+			"0.15x1.3,cx100,cy200,q95,r45,sc0ffee",
 		},
 		{
 			Options{0.15, 1.3, false, 45, false, false, 95, "c0ffee", false, "png", 100, 200, 300, 400, false},
-			"0.15x1.3,r45,q95,sc0ffee,png,cx100,cy200,cw300,ch400",
+			"0.15x1.3,ch400,cw300,cx100,cy200,png,q95,r45,sc0ffee",
 		},
 	}