diff --git a/alib2algo/src/tree/properties/BadCharacterShiftTable.h b/alib2algo/src/tree/properties/BadCharacterShiftTable.h
index 6af59ee93052afd8a675ca031a12b29d10cced48..0f31dc1b26488c80c6873b0b43ec6c159774548c 100644
--- a/alib2algo/src/tree/properties/BadCharacterShiftTable.h
+++ b/alib2algo/src/tree/properties/BadCharacterShiftTable.h
@@ -79,7 +79,7 @@ ext::map < common::ranked_symbol < SymbolType, RankType >, size_t > BadCharacter
 	}
 
 	 // limit the shift by position of symbols within the pattern
-	for ( unsigned i = 0; i < pattern.getContent ( ).size ( ) - 1; i++ ) { // last symbol is not concerned
+	for ( size_t i = 0; i < pattern.getContent ( ).size ( ) - 1; i++ ) { // last symbol is not concerned
 		if ( pattern.getContent ( )[i] == pattern.getSubtreeWildcard ( ) || pattern.getNonlinearVariables ( ).count ( pattern.getContent ( )[i] ) || pattern.getContent ( )[i] == pattern.getVariablesBar ( ) )
 			continue;
 
diff --git a/alib2data/src/common/SparseBoolVector.hpp b/alib2data/src/common/SparseBoolVector.hpp
index e1f0c0ab518681805d201814d0443e2b32e26c0b..b72e8ee26c7c6bb3aadd07519ec52abc6570bd2d 100644
--- a/alib2data/src/common/SparseBoolVector.hpp
+++ b/alib2data/src/common/SparseBoolVector.hpp
@@ -320,7 +320,7 @@ public:
 
 	friend std::ostream & operator << ( std::ostream & out, const common::SparseBoolVector::element & elem ) {
 		out << "(" << elem.run << ", ";
-		for ( unsigned i = 0; i < sizeof ( elem.word ) * BITS_IN_BYTE; ++ i )
+		for ( size_t i = 0; i < sizeof ( elem.word ) * BITS_IN_BYTE; ++ i )
 			out << (bool) ( elem.word & 1u << i );
 		out << ")";
 		return out;