diff --git a/idicon.go b/idicon.go
index 1efda1e..d2f84e9 100644
--- a/idicon.go
+++ b/idicon.go
@@ -18,7 +18,10 @@ func requestHandler(w http.ResponseWriter, r *http.Request) {
 
 	size, err := strconv.Atoi(r.URL.Query().Get("s"))
 	if err != nil {
-		size = 80
+		size, err = strconv.Atoi(r.URL.Query().Get("size"))
+		if err != nil {
+			size = 80
+		}
 	}
 
 	colorScheme := r.URL.Query().Get("c")
diff --git a/idicon_test.go b/idicon_test.go
index 08e182f..65f0e04 100644
--- a/idicon_test.go
+++ b/idicon_test.go
@@ -23,6 +23,9 @@ var gh1 []byte
 //go:embed testdata/a1d0c6e83f027327d8461063f4ac58a6_gh.png
 var gh2 []byte
 
+//go:embed testdata/1a79a4d60de6718e8e5b326e338ae533_s40.png
+var s40 []byte
+
 func testRouter() *mux.Router {
 	router := mux.NewRouter()
 	router.HandleFunc("/avatar/{id}", requestHandler)
@@ -99,6 +102,34 @@ func TestCorrectResponseForAltGHColorSchemeAndPattern(t *testing.T) {
 	}
 }
 
+func TestCorrectResponseForSParam40(t *testing.T) {
+	req, err := http.NewRequest("GET", "/avatar/1a79a4d60de6718e8e5b326e338ae533?s=40", nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	rr := httptest.NewRecorder()
+	testRouter().ServeHTTP(rr, req)
+
+	if !reflect.DeepEqual(rr.Body.Bytes(), s40) {
+		t.Errorf("returned image does not match expected image")
+	}
+}
+
+func TestCorrectResponseForSizeParam40(t *testing.T) {
+	req, err := http.NewRequest("GET", "/avatar/1a79a4d60de6718e8e5b326e338ae533?size=40", nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	rr := httptest.NewRecorder()
+	testRouter().ServeHTTP(rr, req)
+
+	if !reflect.DeepEqual(rr.Body.Bytes(), s40) {
+		t.Errorf("returned image does not match expected image")
+	}
+}
+
 func TestUsesConfig(t *testing.T) {
 	configure("./testdata/testconfig.toml")
 
diff --git a/testdata/1a79a4d60de6718e8e5b326e338ae533_s40.png b/testdata/1a79a4d60de6718e8e5b326e338ae533_s40.png
new file mode 100644
index 0000000..f73cbfa
Binary files /dev/null and b/testdata/1a79a4d60de6718e8e5b326e338ae533_s40.png differ