diff --git a/libraries/stdlib/native-wasm/src/kotlin/text/regex/Pattern.kt b/libraries/stdlib/native-wasm/src/kotlin/text/regex/Pattern.kt
index 1ecf690e2dd..309d8da39ac 100644
--- a/libraries/stdlib/native-wasm/src/kotlin/text/regex/Pattern.kt
+++ b/libraries/stdlib/native-wasm/src/kotlin/text/regex/Pattern.kt
@@ -130,6 +130,9 @@ internal class Pattern(val pattern: String, flags: Int = 0) {
 
                 if (ch == Lexer.CHAR_NAMED_GROUP) {
                     val name = (lexemes.curSpecialToken as NamedGroup).name
+                    if (groupNameToIndex.containsKey(name)) {
+                        throw PatternSyntaxException("Named capturing group <$name> is already defined", pattern, lexemes.curTokenIndex)
+                    }
                     groupNameToIndex[name] = fSet.groupIndex
                 }
             }
diff --git a/libraries/stdlib/test/text/RegexTest.kt b/libraries/stdlib/test/text/RegexTest.kt
index d91a6f4fa93..478bed971ec 100644
--- a/libraries/stdlib/test/text/RegexTest.kt
+++ b/libraries/stdlib/test/text/RegexTest.kt
@@ -174,6 +174,17 @@ class RegexTest {
         assertEquals("123", namedGroups["areaCode"]?.value)
     }
 
+    @Test fun matchDuplicateGroupName() {
+        if (!supportsNamedCapturingGroup) return
+
+        assertFailsWith<IllegalArgumentException> {
+            "(?<hi>hi)|(?<hi>bye)".toRegex()
+        }
+        assertFailsWith<IllegalArgumentException> {
+            Regex("(?<first>\\d+)-(?<first>\\d+)")
+        }
+    }
+
     @Test fun matchOptionalNamedGroup() {
         if (!supportsNamedCapturingGroup) return