diff --git a/pkg/downloader/manager.go b/pkg/downloader/manager.go
index d2adfbc78..2d6918739 100644
--- a/pkg/downloader/manager.go
+++ b/pkg/downloader/manager.go
@@ -480,14 +480,31 @@ func (m *Manager) resolveRepoNames(deps []*chart.Dependency) (map[string]string,
 		if !found {
 			repository := dd.Repository
 			// Add if URL
-			if _, err := url.ParseRequestURI(repository); err != nil {
-				return nil, err
+			_, err := url.ParseRequestURI(repository)
+			if err == nil {
+				reposMap[repository] = repository
+				continue
 			}
 			missing = append(missing, repository)
 		}
 	}
 	if len(missing) > 0 {
-		return nil, ErrRepoNotFound{missing}
+		errorMessage := fmt.Sprintf("no repository definition for %s. Please add them via 'helm repo add'", strings.Join(missing, ", "))
+		// It is common for people to try to enter "stable" as a repository instead of the actual URL.
+		// For this case, let's give them a suggestion.
+		containsNonURL := false
+		for _, repo := range missing {
+			if !strings.Contains(repo, "//") && !strings.HasPrefix(repo, "@") && !strings.HasPrefix(repo, "alias:") {
+				containsNonURL = true
+			}
+		}
+		if containsNonURL {
+			errorMessage += `
+Note that repositories must be URLs or aliases. For example, to refer to the "example"
+repository, use "https://charts.example.com/" or "@example" instead of
+"example". Don't forget to add the repo, too ('helm repo add').`
+		}
+		return nil, errors.New(errorMessage)
 	}
 	return reposMap, nil
 }