diff --git a/config/config.go b/config/config.go
index 59eeee9f..b749833c 100644
--- a/config/config.go
+++ b/config/config.go
@@ -24,6 +24,7 @@ import (
 	"reflect"
 	"regexp"
 	"runtime"
+	"slices"
 	"sort"
 	"strconv"
 	"strings"
@@ -350,7 +351,7 @@ func (s *Module) UnmarshalYAML(unmarshal func(interface{}) error) error {
 	if err := unmarshal((*plain)(s)); err != nil {
 		return err
 	}
-	return nil
+	return s.validate()
 }
 
 // UnmarshalJSON implements the json.Unmarshaler interface.
@@ -390,7 +391,7 @@ func (s *Module) UnmarshalJSON(data []byte) error {
 				return err
 			}
 		default:
-			return fmt.Errorf("invalid duration: %#v", tmp)
+			return fmt.Errorf("invalid duration '%#v'", tmp)
 		}
 	}
 	*s = Module{
@@ -402,6 +403,13 @@ func (s *Module) UnmarshalJSON(data []byte) error {
 		DNS:     tmp.DNS,
 		GRPC:    tmp.GRPC,
 	}
+	return s.validate()
+}
+
+func (s *Module) validate() error {
+	if !slices.Contains([]string{"http", "tcp", "icmp", "dns", "grpc"}, s.Prober) {
+		return fmt.Errorf("prober '%s' is invalid", s.Prober)
+	}
 	return nil
 }
 
diff --git a/config/config_test.go b/config/config_test.go
index 60cd54f7..34c86fdd 100644
--- a/config/config_test.go
+++ b/config/config_test.go
@@ -224,6 +224,11 @@ func TestLoadBadConfigs(t *testing.T) {
 			want:   `error parsing config file: setting body and body_file both are not allowed`,
 			format: []string{"yml", "json"},
 		},
+		{
+			input:  "testdata/invalid-module-prober",
+			want:   `error parsing config file: invalid prober 'hTTp'`,
+			format: []string{"yml", "json"},
+		},
 	}
 	for _, test := range tests {
 		require.NoError(t, yamlToJson(t, test.input))
diff --git a/config/testdata/invalid-module-prober.yml b/config/testdata/invalid-module-prober.yml
new file mode 100644
index 00000000..0b8e17b6
--- /dev/null
+++ b/config/testdata/invalid-module-prober.yml
@@ -0,0 +1,5 @@
+modules:
+  http_2xx:
+    prober: hTTp
+    timeout: 5s
+    http: