diff --git a/specification.rex b/specification.rex
index 4ac4649..c48b945 100644
--- a/specification.rex
+++ b/specification.rex
@@ -3,9 +3,9 @@ macro
     L_BRACKET                       \(
     R_BRACKET                       \)
     SPACE                           \ +     # Space char
-    OPERATOR_OR                     (?i)or
-    OPERATOR_AND                    (?i)and
-    OPERATOR_NOT                    (?i)not
+    OPERATOR_OR                     (?i)\bor\b
+    OPERATOR_AND                    (?i)\band\b
+    OPERATOR_NOT                    (?i)\bnot\b
     TERM_WITH_QUOTES                "([^"]*)"
     TERM_WITHOUT_QUOTES             [a-zA-Z0-9-_]+
     COLON                           \: