diff --git a/src/rules/events.c b/src/rules/events.c
index 25d62c7..ae5f1f1 100644
--- a/src/rules/events.c
+++ b/src/rules/events.c
@@ -601,7 +601,7 @@ static unsigned int reduceExpressionSequence(ruleset *tree,
                                           messageObject,
                                           context,
                                           targetProperty));
-            ++*i;
+            ++*i;  // increment to next expression makes currentExpression invalid
         }
 
         if (targetProperty->type != JSON_BOOL) {
@@ -609,10 +609,12 @@ static unsigned int reduceExpressionSequence(ruleset *tree,
         }
         
 
-        if ((operator == OP_AND && !targetProperty->value.b) || 
-            (operator == OP_OR && targetProperty->value.b)) {
-            while (currentExpression->operator != OP_END) {
-                ++*i;
+        if ((((operator == OP_AND) && !targetProperty->value.b) || 
+             ((operator == OP_OR)  &&  targetProperty->value.b))
+            && (*i < exprs->length)) {
+            // after reduceExpression() index i moved on to next currentExpression
+            currentExpression = &exprs->expressions[*i];
+            while ((currentExpression->operator != OP_END) && (++*i < exprs->length)) {
                 currentExpression = &exprs->expressions[*i];
             }
             return RULES_OK;