diff --git a/core/src/main/java/org/lflang/LinguaFranca.xtext b/core/src/main/java/org/lflang/LinguaFranca.xtext
index 09401074a6..103224e23c 100644
--- a/core/src/main/java/org/lflang/LinguaFranca.xtext
+++ b/core/src/main/java/org/lflang/LinguaFranca.xtext
@@ -393,11 +393,11 @@ SignedInt:
 ;
 
 Forever:
-    'forever' | 'FOREVER'
+    'forever'
 ;
 
 Never:
-    'never' | 'NEVER'
+    'never'
 ;
 
 Literal:
@@ -529,7 +529,7 @@ Token:
     'startup' | 'shutdown' | 'after' | 'deadline' | 'mutation' | 'preamble' |
     'new' | 'federated' | 'at' | 'as' | 'from' | 'widthof' | 'const' | 'method' |
     'interleaved' | 'mode' | 'initial' | 'reset' | 'history' | 'watchdog' |
-    'extends' | 'forever' | 'FOREVER' | 'never' | 'NEVER' |
+    'extends' | 'forever' | 'never' |
 
     // Other terminals
     NEGINT | TRUE | FALSE |
diff --git a/core/src/main/java/org/lflang/ast/ASTUtils.java b/core/src/main/java/org/lflang/ast/ASTUtils.java
index 5cd0be1129..7e55e3cabc 100644
--- a/core/src/main/java/org/lflang/ast/ASTUtils.java
+++ b/core/src/main/java/org/lflang/ast/ASTUtils.java
@@ -948,22 +948,20 @@ public static boolean isZero(String literal) {
    * Report whether the given literal is forever or not.
    *
    * @param literal AST node to inspect.
-   * @return True if the given literal denotes the constant {@code forever} or {@code FOREVER},
-   *     false otherwise.
+   * @return True if the given literal denotes the constant {@code forever}, false otherwise.
    */
   public static boolean isForever(String literal) {
-    return literal != null && (literal.equals("forever") || literal.equals("FOREVER"));
+    return literal != null && literal.equals("forever");
   }
 
   /**
    * Report whether the given literal is never or not.
    *
    * @param literal AST node to inspect.
-   * @return True if the given literal denotes the constant {@code never} or {@code NEVER}, false
-   *     otherwise.
+   * @return True if the given literal denotes the constant {@code never}, false otherwise.
    */
   public static boolean isNever(String literal) {
-    return literal != null && (literal.equals("never") || literal.equals("NEVER"));
+    return literal != null && literal.equals("never");
   }
 
   /**