diff --git a/config/config.go b/config/config.go
index 09eabb041..9a764ace3 100644
--- a/config/config.go
+++ b/config/config.go
@@ -1017,7 +1017,16 @@ func (v *Variable) ValidateTypeAndDefault() error {
 	// If an explicit type is declared, ensure it is valid
 	if v.DeclaredType != "" {
 		if _, ok := typeStringMap[v.DeclaredType]; !ok {
-			return fmt.Errorf("Variable '%s' must be of type string, map, or list - '%s' is not a valid type", v.Name, v.DeclaredType)
+			validTypes := []string{}
+			for k := range typeStringMap {
+				validTypes = append(validTypes, k)
+			}
+			return fmt.Errorf(
+				"Variable '%s' type must be one of [%s] - '%s' is not a valid type",
+				v.Name,
+				strings.Join(validTypes, ", "),
+				v.DeclaredType,
+			)
 		}
 	}
 
diff --git a/config/loader_test.go b/config/loader_test.go
index ace70d90e..a2a2929f2 100644
--- a/config/loader_test.go
+++ b/config/loader_test.go
@@ -684,7 +684,7 @@ func TestLoadFile_badVariableTypes(t *testing.T) {
 	}
 
 	errorStr := err.Error()
-	if !strings.Contains(errorStr, "'bad_type' must be of type string") {
+	if !strings.Contains(errorStr, "'bad_type' type must be one of") {
 		t.Fatalf("bad: expected error has wrong text: %s", errorStr)
 	}
 }