diff --git a/examples/fun.gri b/examples/fun.gri
index aeb7608..ea31b0b 100644
--- a/examples/fun.gri
+++ b/examples/fun.gri
@@ -49,4 +49,4 @@
    (-> (n)
        (* 3 (- n 2))))
 
-(assert-eq? 15 ( (h) 7 ))
\ No newline at end of file
+(assert-eq? 15 ( (h) 7 ))
diff --git a/examples/set.gri b/examples/set.gri
new file mode 100644
index 0000000..84ed350
--- /dev/null
+++ b/examples/set.gri
@@ -0,0 +1,10 @@
+($ a 1)
+(set! a 2)
+(assert-eq? 2 a )
+
+($ (b x) (+ x 1))
+($ (c x) (* x 2))
+($ d b)
+(assert-eq? 3 (d 2))
+(set! d c)
+(assert-eq? 4 (d 2))
\ No newline at end of file
diff --git a/lib/core.cpp b/lib/core.cpp
index fe103ef..e67810e 100644
--- a/lib/core.cpp
+++ b/lib/core.cpp
@@ -1,6 +1,7 @@
 #include "../src/Loader.hpp"
 #include "src/Logger.hpp"
 #include "src/Value.hpp"
+#include "src/opcodes.hpp"
 
 GRINO_ERROR(assertion_error);
 
@@ -345,6 +346,24 @@ extern "C" void lib(grino::Loader& loader)
     return grino::Value::make_nil(args.back()->loc());
   });
 
+  loader.add_static("set!", [](auto& compiler,
+                               auto node,
+                               auto& program,
+                               auto& sym){
+    std::string ident = node->child(1).lock()->repr();
+    auto expr = node->child(2).lock();
+
+    auto entry = sym.find(ident, compiler.scope());
+
+    if (entry)
+      {
+        compiler.compile(expr, program, sym);
+        program.push_instr(grino::OPCODE_STORE_LOCAL, entry->addr);
+      }
+
+    program.push_value(grino::Value::make_nil(node->loc()));
+  });
+
   loader.add_native("eq?", [](auto args){
     auto lhs = args.front();
 
diff --git a/src/Compiler.hpp b/src/Compiler.hpp
index 4e1f555..5b505d2 100644
--- a/src/Compiler.hpp
+++ b/src/Compiler.hpp
@@ -20,6 +20,8 @@ namespace grino
     explicit Compiler(Logger& logger);
     virtual ~Compiler();
 
+    size_t scope() const { return m_scope.size(); }
+
     void compile(std::shared_ptr<Node> node,
                  Program& program,
                  SymTable& sym);