diff --git a/src/main/kotlin/net/sjrx/intellij/plugins/systemdunitfiles/semanticdata/optionvalues/AbstractGrammarEnumOptionValue.kt b/src/main/kotlin/net/sjrx/intellij/plugins/systemdunitfiles/semanticdata/optionvalues/AbstractGrammarEnumOptionValue.kt
new file mode 100644
index 0000000..ca80993
--- /dev/null
+++ b/src/main/kotlin/net/sjrx/intellij/plugins/systemdunitfiles/semanticdata/optionvalues/AbstractGrammarEnumOptionValue.kt
@@ -0,0 +1,40 @@
+package net.sjrx.intellij.plugins.systemdunitfiles.semanticdata.optionvalues
+
+import com.intellij.openapi.project.Project
+import net.sjrx.intellij.plugins.systemdunitfiles.semanticdata.optionvalues.grammar.Combinator
+import net.sjrx.intellij.plugins.systemdunitfiles.semanticdata.optionvalues.grammar.EOF
+import net.sjrx.intellij.plugins.systemdunitfiles.semanticdata.optionvalues.grammar.FlexibleLiteralChoiceTerminal
+import net.sjrx.intellij.plugins.systemdunitfiles.semanticdata.optionvalues.grammar.SequenceCombinator
+
+/**
+ * Enum-style validator backed by the parser-combinator engine instead of a plain set-membership check.
+ *
+ * Same "just give me the valid choices" API as [AbstractEnumOptionValue], but by routing through the
+ * grammar engine each migrated enum gets precise error highlighting and replace-with-valid-choice
+ * quick-fixes for free. The curated choice list is still returned for autocomplete, so completion does
+ * not regress (a bare [grammar.GrammarOptionValue] would suggest nothing).
+ *
+ * Migration plan: move validators in [EnumOptionValues] onto this base one merge request at a time.
+ * This class is intentionally dormant until the first subclass exists — nothing constructs it yet, so
+ * [buildGrammar] is not invoked and the existing suite is unaffected.
+ */
+abstract class AbstractGrammarEnumOptionValue(
+  private val validOptions: Set<String>,
+  validatorName: String,
+) : SimpleGrammarOptionValues(validatorName, buildGrammar(validOptions)) {
+
+  override fun getAutoCompleteOptions(project: Project): Set<String> = validOptions
+
+  override fun invalidValueMessage(key: String, badValue: String): String {
+    return "$key's value '$badValue' does not match one of the expected values: $validOptions"
+  }
+
+  companion object {
+    /**
+     * Turn the set of valid enum spellings into the grammar the engine validates against.
+     */
+    private fun buildGrammar(validOptions: Set<String>): Combinator {
+      return SequenceCombinator(FlexibleLiteralChoiceTerminal(choices = validOptions.toTypedArray(), ignoreCase = false), EOF())
+    }
+  }
+}
diff --git a/src/main/kotlin/net/sjrx/intellij/plugins/systemdunitfiles/semanticdata/optionvalues/EnumOptionValues.kt b/src/main/kotlin/net/sjrx/intellij/plugins/systemdunitfiles/semanticdata/optionvalues/EnumOptionValues.kt
index 71eb8fc..270bbf8 100644
--- a/src/main/kotlin/net/sjrx/intellij/plugins/systemdunitfiles/semanticdata/optionvalues/EnumOptionValues.kt
+++ b/src/main/kotlin/net/sjrx/intellij/plugins/systemdunitfiles/semanticdata/optionvalues/EnumOptionValues.kt
@@ -13,7 +13,7 @@ class EmergencyActionOptionValue : AbstractEnumOptionValue(validOptions, VALIDAT
   }
 }
 
-class KillModeOptionValue : AbstractEnumOptionValue(validOptions, VALIDATOR_NAME) {
+class KillModeOptionValue : AbstractGrammarEnumOptionValue(validOptions, VALIDATOR_NAME) {
 
   companion object {
     private val validOptions: Set<String> = ImmutableSet.of("control-group", "process", "mixed", "none")
diff --git a/src/main/kotlin/net/sjrx/intellij/plugins/systemdunitfiles/semanticdata/optionvalues/grammar/GrammarOptionValue.kt b/src/main/kotlin/net/sjrx/intellij/plugins/systemdunitfiles/semanticdata/optionvalues/grammar/GrammarOptionValue.kt
index a8567bf..1e474d2 100644
--- a/src/main/kotlin/net/sjrx/intellij/plugins/systemdunitfiles/semanticdata/optionvalues/grammar/GrammarOptionValue.kt
+++ b/src/main/kotlin/net/sjrx/intellij/plugins/systemdunitfiles/semanticdata/optionvalues/grammar/GrammarOptionValue.kt
@@ -28,6 +28,15 @@ open class GrammarOptionValue(
     throw IllegalStateException("This should not be called")
   }
 
+  /**
+   * Message for a value that is well-formed but not actually valid (the "semantic" error, e.g. a
+   * value of the right shape that is not one of the allowed choices). Both matching engines call
+   * this, so an override applies regardless of the parse-engine flag. Subclasses that know their
+   * allowed values (e.g. enum validators) override it to name them; the default stays generic.
+   */
+  open fun invalidValueMessage(key: String, badValue: String): String =
+    "$key's value is correctly formatted but seems invalid."
+
   /**
    * Generates problem descriptors based on the value.
    *
@@ -102,9 +111,9 @@ open class GrammarOptionValue(
             }
           }
 
-          holder.registerProblem(property.valueNode.psi, "${property.key}'s value is correctly formatted but seems invalid.", ProblemHighlightType.GENERIC_ERROR_OR_WARNING, tr, *quickFixes.toTypedArray())
+          holder.registerProblem(property.valueNode.psi, invalidValueMessage(property.key, problemToken), ProblemHighlightType.GENERIC_ERROR_OR_WARNING, tr, *quickFixes.toTypedArray())
         } else {
-          holder.registerProblem(property.valueNode.psi, "${property.key}'s value is correctly formatted but seems invalid.", ProblemHighlightType.GENERIC_ERROR_OR_WARNING)
+          holder.registerProblem(property.valueNode.psi, invalidValueMessage(property.key, value), ProblemHighlightType.GENERIC_ERROR_OR_WARNING)
         }
 
 
@@ -166,7 +175,7 @@ open class GrammarOptionValue(
           quickFixes.add(ReplaceInvalidLiteralChoiceQuickFix(bad.start, bad.text, choice))
         }
 
-        holder.registerProblem(property.valueNode.psi, "${property.key}'s value is correctly formatted but seems invalid.", ProblemHighlightType.GENERIC_ERROR_OR_WARNING, tr, *quickFixes.toTypedArray())
+        holder.registerProblem(property.valueNode.psi, invalidValueMessage(property.key, bad.text), ProblemHighlightType.GENERIC_ERROR_OR_WARNING, tr, *quickFixes.toTypedArray())
       }
     }
   }
diff --git a/src/test/kotlin/net/sjrx/intellij/plugins/systemdunitfiles/inspections/InvalidValueInspectionForEnumOptionValueTests.kt b/src/test/kotlin/net/sjrx/intellij/plugins/systemdunitfiles/inspections/InvalidValueInspectionForEnumOptionValueTests.kt
index f9e22bc..e075829 100644
--- a/src/test/kotlin/net/sjrx/intellij/plugins/systemdunitfiles/inspections/InvalidValueInspectionForEnumOptionValueTests.kt
+++ b/src/test/kotlin/net/sjrx/intellij/plugins/systemdunitfiles/inspections/InvalidValueInspectionForEnumOptionValueTests.kt
@@ -303,6 +303,24 @@ class InvalidValueInspectionForKillModeOptionValue : AbstractUnitFileTest() {
     TestCase.assertNotNull(highlightElement)
     TestCase.assertEquals("sigkill", highlightElement!!.text)
   }
+
+  fun testKillModeInvalidValueOffersReplacementQuickFix() {
+    // Fixture Setup
+    val file = """
+           [Service]
+           KillMode=sigkill
+
+           """.trimIndent()
+    setupFileInEditor("file.service", file)
+    enableInspection(InvalidValueInspection::class.java)
+
+    // Exercise SUT
+    val highlights = myFixture.doHighlighting()
+
+    // Verification
+    assertSize(1, highlights)
+    assertContainsQuickfix(highlights[0]!!, "Replace 'sigkill' with 'process'")
+  }
 }
 
 class InvalidValueInspectionForRestartOptionValueTest : AbstractUnitFileTest() {