diff --git a/build.gradle.kts b/build.gradle.kts
index aba53a1..d24ca67 100644
--- a/build.gradle.kts
+++ b/build.gradle.kts
@@ -11,7 +11,7 @@ repositories {
     mavenCentral()
 }
 
-version = "1.4.1-SNAPSHOT"
+version = "1.4.2-SNAPSHOT"
 group = "org.hisp.dhis.lib.expression"
 
 if (project.hasProperty("removeSnapshotSuffix")) {
@@ -107,4 +107,4 @@ sonarqube {
 
 tasks.named("sonar").configure {
     dependsOn(":koverXmlReport")
-}
\ No newline at end of file
+}
diff --git a/src/commonMain/kotlin/org/hisp/dhis/lib/expression/eval/Calculator.kt b/src/commonMain/kotlin/org/hisp/dhis/lib/expression/eval/Calculator.kt
index b2db5a8..57fc36e 100644
--- a/src/commonMain/kotlin/org/hisp/dhis/lib/expression/eval/Calculator.kt
+++ b/src/commonMain/kotlin/org/hisp/dhis/lib/expression/eval/Calculator.kt
@@ -2,6 +2,7 @@ package org.hisp.dhis.lib.expression.eval
 
 import kotlinx.datetime.LocalDate
 import org.hisp.dhis.lib.expression.ast.*
+import org.hisp.dhis.lib.expression.ast.Nodes.Utf8StringNode
 import org.hisp.dhis.lib.expression.ast.UnaryOperator.Companion.negate
 import org.hisp.dhis.lib.expression.spi.*
 
@@ -139,7 +140,7 @@ internal class Calculator(
                 evalToInteger(fn.child(2)))
             NamedFunction.d2_validatePattern -> functions.d2_validatePattern(
                 evalToString(fn.child(0)),
-                evalToString(fn.child(1)))
+                evalToRawString(fn.child(1)))
             NamedFunction.d2_weeksBetween -> functions.d2_weeksBetween(
                 evalToDate(fn.child(0)),
                 evalToDate(fn.child(1)))
@@ -301,6 +302,15 @@ internal class Calculator(
         return eval(node, "String", Typed::toStringTypeCoercion)
     }
 
+    private fun evalToRawString(node: Node<*>): String? {
+        return when (node.getType()) {
+            NodeType.STRING -> node.getRawValue()
+            NodeType.ARGUMENT -> evalToRawString(node.child(0))
+            NodeType.PAR -> evalToRawString(node.child(0))
+            else -> evalToString(node)
+        }
+    }
+
     fun evalToBoolean(node: Node<*>): Boolean? {
         return eval(node, "Boolean", Typed::toBooleanTypeCoercion)
     }
diff --git a/src/commonMain/kotlin/org/hisp/dhis/lib/expression/spi/ExpressionFunctions.kt b/src/commonMain/kotlin/org/hisp/dhis/lib/expression/spi/ExpressionFunctions.kt
index 5fb4fa7..007cbed 100644
--- a/src/commonMain/kotlin/org/hisp/dhis/lib/expression/spi/ExpressionFunctions.kt
+++ b/src/commonMain/kotlin/org/hisp/dhis/lib/expression/spi/ExpressionFunctions.kt
@@ -315,7 +315,7 @@ fun interface ExpressionFunctions {
     }
 
     fun d2_validatePattern(input: String?, regex: String?): Boolean {
-        return input != null && regex != null && input.matches(regex.toRegex())
+        return input != null && regex != null && matchesPattern(input, regex)
     }
 
     fun d2_weeksBetween(start: LocalDate?, end: LocalDate?): Int {
diff --git a/src/commonMain/kotlin/org/hisp/dhis/lib/expression/spi/RegexMatch.kt b/src/commonMain/kotlin/org/hisp/dhis/lib/expression/spi/RegexMatch.kt
new file mode 100644
index 0000000..63928d0
--- /dev/null
+++ b/src/commonMain/kotlin/org/hisp/dhis/lib/expression/spi/RegexMatch.kt
@@ -0,0 +1,3 @@
+package org.hisp.dhis.lib.expression.spi
+
+internal expect fun matchesPattern(input: String, pattern: String): Boolean
diff --git a/src/commonTest/kotlin/org/hisp/dhis/lib/expression/function/ValidatePatternTest.kt b/src/commonTest/kotlin/org/hisp/dhis/lib/expression/function/ValidatePatternTest.kt
index 278129b..817d4a3 100644
--- a/src/commonTest/kotlin/org/hisp/dhis/lib/expression/function/ValidatePatternTest.kt
+++ b/src/commonTest/kotlin/org/hisp/dhis/lib/expression/function/ValidatePatternTest.kt
@@ -29,15 +29,17 @@ internal class ValidatePatternTest {
     fun testValidatePattern_Match() {
         assertTrue(evaluate("d2:validatePattern(\"124\", \"[0-9]+\")"))
         assertTrue(evaluate("d2:validatePattern(\"12x4\", \"[0-9x]+\")"))
+        assertTrue(evaluate("d2:validatePattern(\"John\",(\"[a-zA-Z0-9À-ȕ\\'\\-\\‘\\`\\’\\ ]+\"))"))
     }
 
     @Test
     fun testValidatePattern_NoMatch() {
         assertFalse(evaluate("d2:validatePattern(\"12x4\", \"[0-9]+\")"))
         assertFalse(evaluate("d2:validatePattern(\"ab0\", \"[0-9x]+\")"))
+        assertFalse(evaluate("d2:validatePattern(\"Иван\",(\"[a-zA-Z0-9À-ȕ\\'\\-\\‘\\`\\’\\ ]+\"))"))
     }
 
     private fun evaluate(expression: String): Boolean {
         return Expression(expression, ExpressionMode.RULE_ENGINE_ACTION).evaluate() as Boolean
     }
-}
\ No newline at end of file
+}
diff --git a/src/jsMain/kotlin/org/hisp/dhis/lib/expression/spi/RegexMatch.kt b/src/jsMain/kotlin/org/hisp/dhis/lib/expression/spi/RegexMatch.kt
new file mode 100644
index 0000000..1219efe
--- /dev/null
+++ b/src/jsMain/kotlin/org/hisp/dhis/lib/expression/spi/RegexMatch.kt
@@ -0,0 +1,7 @@
+package org.hisp.dhis.lib.expression.spi
+
+internal actual fun matchesPattern(input: String, pattern: String): Boolean {
+    // Avoid Kotlin stdlib's Regex wrapper which may add the JS `u` flag and reject unknown backslash
+    // escapes. Use RegExp directly with ^(?:...)$ anchoring to replicate full-string matching.
+    return js("new RegExp('^(?:' + pattern + ')$').test(input)") as Boolean
+}
diff --git a/src/jvmMain/kotlin/org/hisp/dhis/lib/expression/spi/RegexMatch.kt b/src/jvmMain/kotlin/org/hisp/dhis/lib/expression/spi/RegexMatch.kt
new file mode 100644
index 0000000..e33e60c
--- /dev/null
+++ b/src/jvmMain/kotlin/org/hisp/dhis/lib/expression/spi/RegexMatch.kt
@@ -0,0 +1,4 @@
+package org.hisp.dhis.lib.expression.spi
+
+internal actual fun matchesPattern(input: String, pattern: String): Boolean =
+    input.matches(pattern.toRegex())
diff --git a/src/nativeMain/kotlin/org/hisp/dhis/lib/expression/spi/RegexMatch.kt b/src/nativeMain/kotlin/org/hisp/dhis/lib/expression/spi/RegexMatch.kt
new file mode 100644
index 0000000..e33e60c
--- /dev/null
+++ b/src/nativeMain/kotlin/org/hisp/dhis/lib/expression/spi/RegexMatch.kt
@@ -0,0 +1,4 @@
+package org.hisp.dhis.lib.expression.spi
+
+internal actual fun matchesPattern(input: String, pattern: String): Boolean =
+    input.matches(pattern.toRegex())