diff --git a/miniapp/miniapp_recipes.cpp b/miniapp/miniapp_recipes.cpp
index c7aefed259dd972247eae9a4c93ebf32d57bf396..8de187b9e2ccf14394c66c208c291aaecec9b7ef 100644
--- a/miniapp/miniapp_recipes.cpp
+++ b/miniapp/miniapp_recipes.cpp
@@ -56,7 +56,7 @@ public:
                             - param_.min_connection_delay_ms};
     }
 
-    cell_size_type num_cells() const { return ncell_; }
+    cell_size_type num_cells() const override { return ncell_; }
 
     cell get_cell(cell_gid_type i) const override {
         auto gen = std::mt19937(i); // replace this with hashing generator...
diff --git a/src/cell_group.hpp b/src/cell_group.hpp
index f72d14b2d499ca31b2599c45470fe24a62b10859..14ea3946ef4cb05a2b644ba6257563bcb328181f 100644
--- a/src/cell_group.hpp
+++ b/src/cell_group.hpp
@@ -52,7 +52,7 @@ public:
     void reset() {
         remove_samplers();
         initialize_cells();
-        for (auto& spike_source: spike_sources) {
+        for (auto& spike_source: spike_sources_) {
             spike_source.source.reset(cell_, 0.f);
         }
     }
diff --git a/src/util/ioutil.hpp b/src/util/ioutil.hpp
index 89fb70dc4b00e104e067c23d5a52c5b79a906dc1..ff000a47bbdf64138c5446d748a42295ea4606ff 100644
--- a/src/util/ioutil.hpp
+++ b/src/util/ioutil.hpp
@@ -39,11 +39,11 @@ public:
     virtual ~basic_null_streambuf() {}
 
 protected:
-    virtual std::streamsize xsputn(const char_type *s,std::streamsize count) {
+    std::streamsize xsputn(const char_type *s,std::streamsize count) override {
         return count;
     }
 
-    virtual int_type overflow(char c) {
+    int_type overflow(int_type c) override {
         return traits_type::not_eof(c);
     }
 };