diff --git a/model/labels/regexp.go b/model/labels/regexp.go
index b2e13abca8..7868967d98 100644
--- a/model/labels/regexp.go
+++ b/model/labels/regexp.go
@@ -533,7 +533,7 @@ func stringMatcherFromRegexpInternal(re *syntax.Regexp) StringMatcher {
 			// we can optimize.
 			switch {
 			// Literal as prefix.
-			case len(re.Sub) == 2 && re.Sub[0].Op == syntax.OpLiteral:
+			case right == nil && len(re.Sub) == 2 && re.Sub[0].Op == syntax.OpLiteral:
 				right = stringMatcherFromRegexpInternal(re.Sub[1])
 				if right != nil {
 					matches = []string{string(re.Sub[0].Rune)}
@@ -541,7 +541,7 @@ func stringMatcherFromRegexpInternal(re *syntax.Regexp) StringMatcher {
 				}
 
 			// Literal as suffix.
-			case len(re.Sub) == 2 && re.Sub[1].Op == syntax.OpLiteral:
+			case left == nil && len(re.Sub) == 2 && re.Sub[1].Op == syntax.OpLiteral:
 				left = stringMatcherFromRegexpInternal(re.Sub[0])
 				if left != nil {
 					matches = []string{string(re.Sub[1].Rune)}
diff --git a/model/labels/regexp_test.go b/model/labels/regexp_test.go
index 3396b9da79..00538aca48 100644
--- a/model/labels/regexp_test.go
+++ b/model/labels/regexp_test.go
@@ -413,6 +413,11 @@ func TestStringMatcherFromRegexp(t *testing.T) {
 		// Case insensitive alternate with same literal prefix and .* suffix.
 		{"(?i:(xyz-016a-ixb-dp.*|xyz-016a-ixb-op.*))", &literalPrefixStringMatcher{prefix: "XYZ-016A-IXB-", prefixCaseSensitive: false, right: orStringMatcher{&literalPrefixStringMatcher{prefix: "DP", prefixCaseSensitive: false, right: anyStringWithoutNewlineMatcher{}}, &literalPrefixStringMatcher{prefix: "OP", prefixCaseSensitive: false, right: anyStringWithoutNewlineMatcher{}}}}},
 		{"(?i)(xyz-016a-ixb-dp.*|xyz-016a-ixb-op.*)", &literalPrefixStringMatcher{prefix: "XYZ-016A-IXB-", prefixCaseSensitive: false, right: orStringMatcher{&literalPrefixStringMatcher{prefix: "DP", prefixCaseSensitive: false, right: anyStringWithoutNewlineMatcher{}}, &literalPrefixStringMatcher{prefix: "OP", prefixCaseSensitive: false, right: anyStringWithoutNewlineMatcher{}}}}},
+		// Concatenated variable length selectors are not supported.
+		{"foo.*.*", nil},
+		{"foo.+.+", nil},
+		{".*.*foo", nil},
+		{".+.+foo", nil},
 	} {
 		c := c
 		t.Run(c.pattern, func(t *testing.T) {