diff --git a/README.md b/README.md
index a9b19ef..a082a0b 100644
--- a/README.md
+++ b/README.md
@@ -172,6 +172,8 @@ Parsing [linguist/samples](https://github.com/github/linguist/tree/master/sample
 
 - [Heuristics for ".as" extension](https://github.com/github/linguist/blob/223c00bb80eff04788e29010f98c5778993d2b2a/lib/linguist/heuristics.yml#L67) in ActionScript could not be parsed, due to unsupported positive lookahead in RE2 regexp engine.
 
+- [Heuristics for ".csc", ".gsc" and ".gsh" extension](https://github.com/github/linguist/blob/7469c7982d93f2ad922230d712f586a353dc1a42/lib/linguist/heuristics.yml#L650-L651) in GSC could not be parsed, due to unsupported non-backtracking subexpressions in RE2 regexp engine.
+
 - As of [Linguist v5.3.2](https://github.com/github/linguist/releases/tag/v5.3.2) it is using [flex-based scanner in C for tokenization](https://github.com/github/linguist/pull/3846). Enry still uses [extract_token](https://github.com/github/linguist/pull/3846/files#diff-d5179df0b71620e3fac4535cd1368d15L60) regex-based algorithm. See [#193](https://github.com/src-d/enry/issues/193).
 
 - Bayesian classifier can't distinguish "SQL" from "PLpgSQL. See [#194](https://github.com/src-d/enry/issues/194).
diff --git a/data/content.go b/data/content.go
index 00ea011..2872231 100644
--- a/data/content.go
+++ b/data/content.go
@@ -697,12 +697,7 @@ var ContentHeuristics = map[string]*Heuristics{
 			regexp.MustCompile(`(?m)^(\s*namespace\s*[\w\.]+\s*{|\s*\/\/)`),
 		),
 	},
-	".csc": &Heuristics{
-		rule.Or(
-			rule.MatchingLanguages("GSC"),
-			regexp.MustCompile(`(?m)^\s*#\s*(?:using|insert|include|define|namespace)[ \t]+\w|^\s*(?>(?:autoexec|private)\s+){0,2}function\s+(?>(?:autoexec|private)\s+){0,2}\w+\s*\(|\b(?:level|self)[ \t]+thread[ \t]+(?:\[\[[ \t]*(?>\w+\.)*\w+[ \t]*\]\]|\w+)[ \t]*\([^\r\n\)]*\)[ \t]*;|^[ \t]*#[ \t]*(?:precache|using_animtree)[ \t]*\(`),
-		),
-	},
+	".csc": &Heuristics{},
 	".csl": &Heuristics{
 		rule.Or(
 			rule.MatchingLanguages("XML"),
@@ -879,18 +874,8 @@ var ContentHeuristics = map[string]*Heuristics{
 			regexp.MustCompile(`(?m)^\[indent=[0-9]+\]`),
 		),
 	},
-	".gsc": &Heuristics{
-		rule.Or(
-			rule.MatchingLanguages("GSC"),
-			regexp.MustCompile(`(?m)^\s*#\s*(?:using|insert|include|define|namespace)[ \t]+\w|^\s*(?>(?:autoexec|private)\s+){0,2}function\s+(?>(?:autoexec|private)\s+){0,2}\w+\s*\(|\b(?:level|self)[ \t]+thread[ \t]+(?:\[\[[ \t]*(?>\w+\.)*\w+[ \t]*\]\]|\w+)[ \t]*\([^\r\n\)]*\)[ \t]*;|^[ \t]*#[ \t]*(?:precache|using_animtree)[ \t]*\(`),
-		),
-	},
-	".gsh": &Heuristics{
-		rule.Or(
-			rule.MatchingLanguages("GSC"),
-			regexp.MustCompile(`(?m)^\s*#\s*(?:using|insert|include|define|namespace)[ \t]+\w|^\s*(?>(?:autoexec|private)\s+){0,2}function\s+(?>(?:autoexec|private)\s+){0,2}\w+\s*\(|\b(?:level|self)[ \t]+thread[ \t]+(?:\[\[[ \t]*(?>\w+\.)*\w+[ \t]*\]\]|\w+)[ \t]*\([^\r\n\)]*\)[ \t]*;|^[ \t]*#[ \t]*(?:precache|using_animtree)[ \t]*\(`),
-		),
-	},
+	".gsc": &Heuristics{},
+	".gsh": &Heuristics{},
 	".h": &Heuristics{
 		rule.Or(
 			rule.MatchingLanguages("Objective-C"),
diff --git a/internal/code-generator/generator/heuristics.go b/internal/code-generator/generator/heuristics.go
index bd8a9af..0b0c2f4 100644
--- a/internal/code-generator/generator/heuristics.go
+++ b/internal/code-generator/generator/heuristics.go
@@ -39,7 +39,7 @@ func GenHeuristics(fileToParse, _, outPath, tmplPath, tmplName, commit string) e
 
 // loadHeuristics transforms parsed YAML to map[".ext"]->IR for code generation.
 func loadHeuristics(yaml *Heuristics) (map[string][]*LanguagePattern, error) {
-	var patterns = make(map[string][]*LanguagePattern)
+	patterns := make(map[string][]*LanguagePattern)
 	for _, disambiguation := range yaml.Disambiguations {
 		var rules []*LanguagePattern
 		for _, rule := range disambiguation.Rules {
@@ -161,13 +161,14 @@ func parseYaml(file string) (*Heuristics, error) {
 // isUnsupportedRegexpSyntax filters regexp syntax that is not supported by RE2.
 // In particular, we stumbled up on usage of next cases:
 // - lookbehind & lookahead
+// - non-backtracking subexpressions
 // - named & numbered capturing group/after text matching
 // - backreference
 // - possessive quantifier
 // For referece on supported syntax see https://github.com/google/re2/wiki/Syntax
 func isUnsupportedRegexpSyntax(reg string) bool {
 	return strings.Contains(reg, `(?<`) || strings.Contains(reg, `(?=`) || strings.Contains(reg, `(?!`) ||
-		strings.Contains(reg, `\1`) || strings.Contains(reg, `*+`) ||
+		strings.Contains(reg, `(?>`) || strings.Contains(reg, `\1`) || strings.Contains(reg, `*+`) ||
 		// See https://github.com/github/linguist/pull/4243#discussion_r246105067
 		(strings.HasPrefix(reg, multilinePrefix+`/`) && strings.HasSuffix(reg, `/`))
 }
diff --git a/internal/code-generator/generator/test_files/content.gold b/internal/code-generator/generator/test_files/content.gold
index 00ea011..2872231 100644
--- a/internal/code-generator/generator/test_files/content.gold
+++ b/internal/code-generator/generator/test_files/content.gold
@@ -697,12 +697,7 @@ var ContentHeuristics = map[string]*Heuristics{
 			regexp.MustCompile(`(?m)^(\s*namespace\s*[\w\.]+\s*{|\s*\/\/)`),
 		),
 	},
-	".csc": &Heuristics{
-		rule.Or(
-			rule.MatchingLanguages("GSC"),
-			regexp.MustCompile(`(?m)^\s*#\s*(?:using|insert|include|define|namespace)[ \t]+\w|^\s*(?>(?:autoexec|private)\s+){0,2}function\s+(?>(?:autoexec|private)\s+){0,2}\w+\s*\(|\b(?:level|self)[ \t]+thread[ \t]+(?:\[\[[ \t]*(?>\w+\.)*\w+[ \t]*\]\]|\w+)[ \t]*\([^\r\n\)]*\)[ \t]*;|^[ \t]*#[ \t]*(?:precache|using_animtree)[ \t]*\(`),
-		),
-	},
+	".csc": &Heuristics{},
 	".csl": &Heuristics{
 		rule.Or(
 			rule.MatchingLanguages("XML"),
@@ -879,18 +874,8 @@ var ContentHeuristics = map[string]*Heuristics{
 			regexp.MustCompile(`(?m)^\[indent=[0-9]+\]`),
 		),
 	},
-	".gsc": &Heuristics{
-		rule.Or(
-			rule.MatchingLanguages("GSC"),
-			regexp.MustCompile(`(?m)^\s*#\s*(?:using|insert|include|define|namespace)[ \t]+\w|^\s*(?>(?:autoexec|private)\s+){0,2}function\s+(?>(?:autoexec|private)\s+){0,2}\w+\s*\(|\b(?:level|self)[ \t]+thread[ \t]+(?:\[\[[ \t]*(?>\w+\.)*\w+[ \t]*\]\]|\w+)[ \t]*\([^\r\n\)]*\)[ \t]*;|^[ \t]*#[ \t]*(?:precache|using_animtree)[ \t]*\(`),
-		),
-	},
-	".gsh": &Heuristics{
-		rule.Or(
-			rule.MatchingLanguages("GSC"),
-			regexp.MustCompile(`(?m)^\s*#\s*(?:using|insert|include|define|namespace)[ \t]+\w|^\s*(?>(?:autoexec|private)\s+){0,2}function\s+(?>(?:autoexec|private)\s+){0,2}\w+\s*\(|\b(?:level|self)[ \t]+thread[ \t]+(?:\[\[[ \t]*(?>\w+\.)*\w+[ \t]*\]\]|\w+)[ \t]*\([^\r\n\)]*\)[ \t]*;|^[ \t]*#[ \t]*(?:precache|using_animtree)[ \t]*\(`),
-		),
-	},
+	".gsc": &Heuristics{},
+	".gsh": &Heuristics{},
 	".h": &Heuristics{
 		rule.Or(
 			rule.MatchingLanguages("Objective-C"),