diff --git a/example.script b/example.script
index ce2dd49..64a1509 100644
--- a/example.script
+++ b/example.script
@@ -1,4 +1,4 @@
-/*x := 1
+x := 1
 y := 1
 
 i := 60
@@ -8,10 +8,4 @@ while i {
 	x = z
 	print(z)
 	i = i - 1
-}*/
-
-f := 2.0
-
-a := int(pow(f, 2.0)) + 1
-
-print(a)
+}
diff --git a/main.c b/main.c
index e5a8669..f202cca 100644
--- a/main.c
+++ b/main.c
@@ -9,6 +9,7 @@
 #include "lex.h"
 #include "parse.h"
 #include "util.h"
+#include "vm.h"
 
 static void usage(const char *prgname);
 static void die(const char *fmt, ...);
@@ -155,6 +156,13 @@ int main(int argc, const char **argv) {
 	if (opt_emit_ir)
 		print_ir(&ir, funcs);
 	/* run the IR */
-	/* TODO... */
+	if (!opt_dry) {
+		run(&ir, funcs);
+		if (err) {
+			irtoks_term(&ir);
+			fprintf(stderr, C_IRED "Runtime error" C_RESET " in " C_CYAN "%s" C_RESET ":%zu:%zu: %s\n", filename, err_ln, err_col, errbuf);
+			return 1;
+		}
+	}
 	irtoks_term(&ir);
 }
diff --git a/parse.c b/parse.c
index 3efd4f1..11100e8 100644
--- a/parse.c
+++ b/parse.c
@@ -260,12 +260,7 @@ static void expr(IRToks *out_ir, TokList *toks, Map *funcs, Scope *parent_sc, To
 			if (v->kind == TokVal) {
 				/* immediately negate value */
 				t->tok.kind = TokVal;
-				t->tok.Val.type.kind = v->Val.type.kind;
-				switch (v->Val.type.kind) {
-					case TypeInt:   t->tok.Val.Int   = -v->Val.Int;   break;
-					case TypeFloat: t->tok.Val.Float = -v->Val.Float; break;
-					default: ASSERT_UNREACHED();
-				}
+				t->tok.Val = eval_unary(IRNeg, &v->Val);
 			} else {
 				/* use the predefined storage address if it was requested and we're on the last operation */
 				size_t res_addr;
diff --git a/runtime.c b/runtime.c
index d848f3c..b04c8eb 100644
--- a/runtime.c
+++ b/runtime.c
@@ -45,6 +45,32 @@ Value eval_arith(IRInstr instr, const Value *lhs, const Value *rhs) {
 	return (Value){0};
 }
 
+Value eval_unary(IRInstr instr, const Value *v) {
+	switch (instr) {
+		case IRSet:
+			return *v;
+		case IRNeg:
+			if (v->type.kind == TypeInt)
+				return (Value){ .type.kind = TypeInt, .Int = -v->Int };
+			else if (v->type.kind == TypeFloat)
+				return (Value){ .type.kind = TypeFloat, .Float = -v->Float };
+			else {
+				set_err("Unsupported types for operation '%s'", irinstr_str[instr]);
+				return (Value){0};
+			}
+		default:
+			ASSERT_UNREACHED();
+	}
+}
+
+bool is_nonzero(const Value *v) {
+	switch (v->type.kind) {
+		case TypeInt:   return v->Int   != 0;
+		case TypeFloat: return v->Float != 0.0;
+		default: ASSERT_UNREACHED();
+	}
+}
+
 Value zero_val(Type ty) {
 	Value ret;
 	ret.type = ty;
diff --git a/runtime.h b/runtime.h
index 170982c..9205218 100644
--- a/runtime.h
+++ b/runtime.h
@@ -4,6 +4,8 @@
 #include "ir.h"
 
 Value eval_arith(IRInstr instr, const Value *lhs, const Value *rhs);
+Value eval_unary(IRInstr instr, const Value *v);
+bool is_nonzero(const Value *v);
 Value zero_val(Type ty);
 
 #endif /* RUNTIME_H */
diff --git a/vm.c b/vm.c
index a199988..446b3d4 100644
--- a/vm.c
+++ b/vm.c
@@ -1 +1,93 @@
 #include "vm.h"
+
+#include "runtime.h"
+#include "util.h"
+
+#define INIT_STACK_CAP 256
+
+typedef struct Stack {
+	Value *mem;
+	size_t len, cap;
+} Stack;
+
+static Stack stack_make(void);
+static void stack_term(Stack *s);
+static void stack_fit(Stack *s, size_t idx);
+
+static Stack stack_make(void) {
+	Stack s;
+	s.mem = xmalloc(sizeof(Value) * INIT_STACK_CAP);
+	s.cap = INIT_STACK_CAP;
+	s.len = 0;
+	return s;
+}
+
+static void stack_term(Stack *s) {
+	free(s->mem);
+}
+
+static void stack_fit(Stack *s, size_t idx) {
+	size_t size = idx+1;
+	if (size > s->cap) {
+		s->mem = xrealloc(s->mem, sizeof(Value) * (size + (s->cap *= 2)));
+	}
+}
+
+static Value *irparam_to_val(Stack *s, IRParam *v) {
+	if (v->kind == IRParamLiteral)
+		return &v->Literal;
+	else if (v->kind == IRParamAddr)
+		return &s->mem[v->Addr];
+	else
+		ASSERT_UNREACHED();
+}
+
+void run(const IRToks *ir, const BuiltinFunc *builtin_funcs) {
+	Stack s = stack_make();
+	for (size_t i = 0; i < ir->len;) {
+		IRTok *instr = &ir->toks[i];
+		switch (instr->instr) {
+			case IRSet:
+			case IRNeg:
+				stack_fit(&s, instr->Unary.addr);
+				s.mem[instr->Unary.addr] = eval_unary(instr->instr, irparam_to_val(&s, &instr->Unary.val));
+				break;
+			case IRAdd:
+			case IRSub:
+			case IRDiv:
+			case IRMul:
+				stack_fit(&s, instr->Arith.addr);
+				s.mem[instr->Arith.addr] = eval_arith(instr->instr,
+					irparam_to_val(&s, &instr->Arith.lhs),
+					irparam_to_val(&s, &instr->Arith.rhs)
+				);
+				break;
+			case IRJmp:
+				i = instr->Jmp.iaddr;
+				continue;
+			case IRJnz:
+				if (is_nonzero(irparam_to_val(&s, &instr->CJmp.condition))) {
+					i = instr->Jmp.iaddr;
+					continue;
+				}
+				break;
+			case IRCallInternal: {
+				const BuiltinFunc *f = &builtin_funcs[instr->CallI.fid];
+				Value *args = xmalloc(sizeof(Value) * f->n_args);
+				for (size_t i = 0; i < f->n_args; i++)
+					args[i] = *irparam_to_val(&s, &instr->CallI.args[i]);
+
+				stack_fit(&s, instr->CallI.ret_addr);
+				s.mem[instr->CallI.ret_addr] = f->func(args);
+
+				free(args);
+				break;
+			}
+			default:
+				ASSERT_UNREACHED();
+		}
+
+		i++;
+	}
+	stack_term(&s);
+}
diff --git a/vm.h b/vm.h
index 40420f6..8378da1 100644
--- a/vm.h
+++ b/vm.h
@@ -1,4 +1,8 @@
 #ifndef __VM_H__
 #define __VM_H__
 
+#include "ir.h"
+
+void run(const IRToks *ir, const BuiltinFunc *builtin_funcs);
+
 #endif /* VM_H */