diff --git a/alib/src/grammar/Rule.cpp b/alib/src/grammar/Rule.cpp
index 1e6a4224043dfd73559df41d96c4a939121e57f8..8113b2ca37d6dcc924e11298ffb744870e202fe5 100644
--- a/alib/src/grammar/Rule.cpp
+++ b/alib/src/grammar/Rule.cpp
@@ -76,6 +76,7 @@ bool Rule::operator <(const Rule& other) const {
 			return *left < *otherLeft;
 		}
 		left++;
+		otherLeft++;
 	}
 
 	list<Symbol>::const_iterator right = rightSide.begin();
@@ -85,6 +86,7 @@ bool Rule::operator <(const Rule& other) const {
 			return *right < *otherRight;
 		}
 		right++;
+		otherRight++;
 	}
 
 	return false;