commit - 64e18a8d1ef9f178f91aed840a371f3785c4d188
commit + 9ffce56b80990611dbb20ba6c4af4df4f9846140
blob - 7c35d24aaef3e10d308c0e2cd9547e15b25d392c
blob + 4b981c1ef6945cc4f45b64af54f0ec37211e1deb
--- http.go
+++ http.go
@@ -5,6 +5,7 @@ import (
 	"io"
 	"net/http"
 	"net/url"
+	"strings"
 )
 
 const versionPrefix = "/v1"
@@ -29,15 +30,22 @@ func NewRequest(method, url, username, password string
 	return req, nil
 }
 
+// filterEncode url-encodes the filter expression expr in the required
+// format to be included in a request. Notably, spaces need to be encoded
+// as "%20", not "+" as returned by the url package.
+func filterEncode(expr string) string {
+	v := url.Values{}
+	v.Set("filter", expr)
+	return strings.ReplaceAll(v.Encode(), "+", "%20")
+}
+
 func (c *Client) get(path, filter string) (*http.Response, error) {
 	u, err := url.Parse("https://" + c.addr + versionPrefix + path)
 	if err != nil {
 		return nil, err
 	}
 	if filter != "" {
-		v := url.Values{}
-		v.Set("filter", filter)
-		u.RawQuery = v.Encode()
+		u.RawQuery = filterEncode(filter)
 	}
 	req, err := NewRequest(http.MethodGet, u.String(), c.username, c.password, nil)
 	if err != nil {
blob - /dev/null
blob + 91468315a23fb23055b378cfef60bdd8c091ffa1 (mode 644)
--- /dev/null
+++ http_test.go
@@ -0,0 +1,13 @@
+package icinga
+
+import "testing"
+
+func TestFilterEncode(t *testing.T) {
+	expr := `match("*.example.com"), host.name) && "test" in host.groups`
+	want := "filter=match%28%22%2A.example.com%22%29%2C%20host.name%29%20%26%26%20%22test%22%20in%20host.groups"
+	got := filterEncode(expr)
+	if want != got {
+		t.Fail()
+	}
+	t.Logf("want %s, got %s", want, got)
+}
blob - e6e5d8c1eac900a0fce5682be080cdc969454f7e
blob + 46576a0932c31df245fbdeb69470db5308629138
--- icinga_test.go
+++ icinga_test.go
@@ -200,6 +200,6 @@ func TestNonExistentService(t *testing.T) {
 	if err == nil {
 		t.Fail()
 	}
-	t.Logf("lookup %s: %v", name, err)
+	t.Log(err)
 	t.Logf("%+v", service)
 }