diff --git a/cmake/compiler_warnings.cmake b/cmake/compiler_warnings.cmake
index d8dc90c05..38b442e83 100644
--- a/cmake/compiler_warnings.cmake
+++ b/cmake/compiler_warnings.cmake
@@ -20,6 +20,9 @@ set(CLANG_ONLY_WARNINGS
   "-Wno-c++98-compat"
   "-Wno-c++98-compat-pedantic"
   "-Wno-zero-length-array"
+  "-Wc99-extensions"
+  "-Wsuggest-override"
+  "-Winconsistent-missing-override"
 )
 set(MSVC_WARNINGS "/W3")
 
diff --git a/src/math/lp/static_matrix.h b/src/math/lp/static_matrix.h
index 08db2245d..3c422c1f9 100644
--- a/src/math/lp/static_matrix.h
+++ b/src/math/lp/static_matrix.h
@@ -119,9 +119,13 @@ public:
 
     void init_empty_matrix(unsigned m, unsigned n);
 
+#ifdef Z3DEBUG
+    unsigned row_count() const override { return static_cast<unsigned>(m_rows.size()); }
+    unsigned column_count() const override { return static_cast<unsigned>(m_columns.size()); }
+#else
     unsigned row_count() const { return static_cast<unsigned>(m_rows.size()); }
-
     unsigned column_count() const { return static_cast<unsigned>(m_columns.size()); }
+#endif
 
     unsigned lowest_row_in_column(unsigned col);
 
@@ -197,7 +201,11 @@ public:
 
     void cross_out_row_from_column(unsigned col, unsigned k);
 
+#ifdef Z3DEBUG
+    T get_elem(unsigned i, unsigned j) const override;
+#else
     T get_elem(unsigned i, unsigned j) const;
+#endif
 
 
     unsigned number_of_non_zeroes_in_column(unsigned j) const { return static_cast<unsigned>(m_columns[j].size()); }
@@ -218,8 +226,8 @@ public:
 #ifdef Z3DEBUG
     unsigned get_number_of_rows() const { return row_count(); }
     unsigned get_number_of_columns() const { return column_count(); }
-    virtual void set_number_of_rows(unsigned /*m*/) { }
-    virtual void set_number_of_columns(unsigned /*n*/) { }
+    void set_number_of_rows(unsigned /*m*/) override { }
+    void set_number_of_columns(unsigned /*n*/) override { }
 #endif
 
     T get_balance() const;