diff --git a/src/SQLParserResult.cpp b/src/SQLParserResult.cpp
index 47a5300..1af1c52 100644
--- a/src/SQLParserResult.cpp
+++ b/src/SQLParserResult.cpp
@@ -32,11 +32,11 @@ namespace hsql {
     statements_.push_back(stmt);
   }
 
-  const SQLStatement* SQLParserResult::getStatement(int index) const {
+  const SQLStatement* SQLParserResult::getStatement(size_t index) const {
     return statements_[index];
   }
 
-  SQLStatement* SQLParserResult::getMutableStatement(int index) {
+  SQLStatement* SQLParserResult::getMutableStatement(size_t index) {
     return statements_[index];
   }
 
diff --git a/src/SQLParserResult.h b/src/SQLParserResult.h
index 939aa3d..1e903aa 100644
--- a/src/SQLParserResult.h
+++ b/src/SQLParserResult.h
@@ -48,10 +48,10 @@ namespace hsql {
     void addStatement(SQLStatement* stmt);
 
     // Gets the SQL statement with the given index.
-    const SQLStatement* getStatement(int index) const;
+    const SQLStatement* getStatement(size_t index) const;
 
     // Gets the non const SQL statement with the given index.
-    SQLStatement* getMutableStatement(int index);
+    SQLStatement* getMutableStatement(size_t index);
 
     // Get the list of all statements.
     const std::vector<SQLStatement*>& getStatements() const;