diff --git a/pkg/labels/regexp.go b/pkg/labels/regexp.go
index f0589f755d..6c8a131011 100644
--- a/pkg/labels/regexp.go
+++ b/pkg/labels/regexp.go
@@ -80,9 +80,6 @@ func findSetMatches(re *syntax.Regexp, base string) []string {
 			return found
 		}
 	case syntax.OpCharClass:
-		if len(base) == 0 {
-			return nil
-		}
 		if len(re.Rune) == 1 {
 			return []string{base + string(re.Rune)}
 		}
@@ -99,13 +96,10 @@ func findSetMatches(re *syntax.Regexp, base string) []string {
 		}
 		for i := 0; i < len(re.Rune); i = i + 2 {
 			lo, hi := re.Rune[i], re.Rune[i+1]
-			if hi == lo {
-				matches = append(matches, base+string(hi))
-			} else {
-				for c := lo; c <= hi; c++ {
-					matches = append(matches, base+string(c))
-				}
+			for c := lo; c <= hi; c++ {
+				matches = append(matches, base+string(c))
 			}
+
 		}
 		return matches
 	default:
diff --git a/pkg/labels/regexp_test.go b/pkg/labels/regexp_test.go
index 03bd4a5c18..2dba236710 100644
--- a/pkg/labels/regexp_test.go
+++ b/pkg/labels/regexp_test.go
@@ -116,7 +116,7 @@ func TestFindSetMatches(t *testing.T) {
 		{"bar|b|buzz", []string{"bar", "b", "buzz"}},
 		// Simple sets containing escaped characters.
 		{"fo\\.o|bar\\?|\\^baz", []string{"fo.o", "bar?", "^baz"}},
-
+		{"[abc]d", []string{"ad", "bd", "cd"}},
 		// high low charset different => A(B[CD]|EF)|BC[XY]
 		{"ABC|ABD|AEF|BCX|BCY", []string{"ABC", "ABD", "AEF", "BCX", "BCY"}},
 		// triple concat