diff --git a/libasn1parser/asn1p_class.c b/libasn1parser/asn1p_class.c
index 666e0a2..3312e4d 100644
--- a/libasn1parser/asn1p_class.c
+++ b/libasn1parser/asn1p_class.c
@@ -29,7 +29,7 @@
 
 	columns = 0;
 	TQ_FOR(field, &oclass->members, next) {
-		int fieldIdLen = strlen(field->Identifier);
+		size_t fieldIdLen = strlen(field->Identifier);
 		if(fieldIdLen > row->max_identifier_length)
 			row->max_identifier_length = fieldIdLen;
 		row->column[columns].field = field;
@@ -42,10 +42,9 @@
 
 void
 asn1p_ioc_row_delete(asn1p_ioc_row_t *row) {
-	int i;
 	if(row) {
 		if(row->column) {
-			for(i = 0; i < row->columns; i++) {
+			for(size_t i = 0; i < row->columns; i++) {
 				if(!row->column[i].new_ref && row->column[i].value) {
 					/* 
 					 * Field 'reference' comes from asn1fix_cws.c :
@@ -94,8 +93,7 @@
 
 struct asn1p_ioc_cell_s *
 asn1p_ioc_row_cell_fetch(asn1p_ioc_row_t *row, const char *fieldname) {
-	int i;
-	for(i = 0; i < row->columns; i++) {
+	for(size_t i = 0; i < row->columns; i++) {
 		if(strcmp(row->column[i].field->Identifier, fieldname) == 0)
 			return &row->column[i];
 	}
diff --git a/libasn1parser/asn1p_class.h b/libasn1parser/asn1p_class.h
index 08fd374..3fd27ef 100644
--- a/libasn1parser/asn1p_class.h
+++ b/libasn1parser/asn1p_class.h
@@ -14,8 +14,8 @@
 		struct asn1p_expr_s *value;	/* may be left uninitialized */
 		int new_ref;
 	} *column;
-	int columns;
-	int max_identifier_length;
+	size_t columns;
+	size_t max_identifier_length;
 } asn1p_ioc_row_t;
 
 asn1p_ioc_row_t *asn1p_ioc_row_new(struct asn1p_expr_s *oclass);
diff --git a/libasn1parser/asn1p_constr.c b/libasn1parser/asn1p_constr.c
index a9e939d..e83b2f8 100644
--- a/libasn1parser/asn1p_constr.c
+++ b/libasn1parser/asn1p_constr.c
@@ -24,6 +24,8 @@
 
 int asn1p_constraint_compare(const asn1p_constraint_t *a,
                              const asn1p_constraint_t *b) {
+    (void)a;
+    (void)b;
     assert(!"Constraint comparison is not implemented");
     return -1;
 }
diff --git a/libasn1parser/asn1p_expr.c b/libasn1parser/asn1p_expr.c
index 4383ea1..eb5fc79 100644
--- a/libasn1parser/asn1p_expr.c
+++ b/libasn1parser/asn1p_expr.c
@@ -346,9 +346,8 @@
 			free(expr->specializations.pspec);
 		}
 		if(expr->object_class_matrix.row) {
-			int row;
-			for(row = 0; row < expr->object_class_matrix.rows; row++) {
-				asn1p_ioc_row_delete(expr->object_class_matrix.row[row]);
+            for(size_t row = 0; row < expr->object_class_matrix.rows; row++) {
+                asn1p_ioc_row_delete(expr->object_class_matrix.row[row]);
 			}
 			free(expr->object_class_matrix.row);
 		}
diff --git a/libasn1parser/asn1p_expr.h b/libasn1parser/asn1p_expr.h
index 524f532..c391361 100644
--- a/libasn1parser/asn1p_expr.h
+++ b/libasn1parser/asn1p_expr.h
@@ -181,8 +181,8 @@
 	/* Information Object Class matrix, specific for this class */
 	struct asn1p_ioc_matrix_s {
 		asn1p_ioc_row_t **row;
-		int rows;
-		int max_identifier_length;
+		size_t rows;
+		size_t max_identifier_length;
 	} object_class_matrix;
 
 	/*
diff --git a/libasn1parser/asn1p_ref.c b/libasn1parser/asn1p_ref.c
index 64f51b4..ebb1731 100644
--- a/libasn1parser/asn1p_ref.c
+++ b/libasn1parser/asn1p_ref.c
@@ -24,7 +24,7 @@
 asn1p_ref_free(asn1p_ref_t *ref) {
 	if(ref) {
 		if(ref->components) {
-			int i = ref->comp_count;
+			size_t i = ref->comp_count;
 			while(i--) {
 				free(ref->components[i].name);
 				ref->components[i].name = 0;
@@ -127,8 +127,7 @@
 
 	newref = asn1p_ref_new(ref->_lineno, ref->module);
 	if(newref) {
-		int i;
-		for(i = 0; i < ref->comp_count; i++) {
+		for(size_t i = 0; i < ref->comp_count; i++) {
 			if(asn1p_ref_add_component(newref,
 				ref->components[i].name,
 				ref->components[i].lex_type
diff --git a/libasn1parser/asn1p_ref.h b/libasn1parser/asn1p_ref.h
index 776289b..c5a99c1 100644
--- a/libasn1parser/asn1p_ref.h
+++ b/libasn1parser/asn1p_ref.h
@@ -34,8 +34,8 @@
 		char *name;	/* An identifier */
 	} *components;
 
-	int comp_count;	/* Number of the components in the reference name. */
-	int comp_size;	/* Number of allocated structures */
+	size_t comp_count;	/* Number of the components in the reference name. */
+	size_t comp_size;	/* Number of allocated structures */
 
 	struct asn1p_module_s *module;	/* Defined in module */
 	int _lineno;	/* Number of line in the file */