diff --git a/bsc/codegen/__init__.py b/bsc/codegen/__init__.py
index 62051b6..f8114b1 100644
--- a/bsc/codegen/__init__.py
+++ b/bsc/codegen/__init__.py
@@ -161,6 +161,13 @@ def gen_stmt(self, stmt):
             self.gen_expr(stmt.expr)
         elif isinstance(stmt, ConstDecl):
             self.gen_const_decl(stmt)
+        elif isinstance(stmt, WhileStmt):
+            while_stmt = LuaWhile(self.gen_expr(stmt.cond))
+            old_block = self.cur_block
+            self.cur_block = LuaBlock()
+            self.gen_stmts(stmt.stmts)
+            self.cur_block = old_block
+            self.cur_block.add_stmt(while_stmt)
 
     ## == Expressions ===========================================
 
diff --git a/bsc/codegen/lua_ast.py b/bsc/codegen/lua_ast.py
index 179505d..6a46831 100644
--- a/bsc/codegen/lua_ast.py
+++ b/bsc/codegen/lua_ast.py
@@ -33,13 +33,13 @@ def __init__(self, name, args, is_static = False):
 # Statements
 
 class LuaWhile:
-    def __init__(self, cond, stmts):
+    def __init__(self, cond, stmts = []):
         self.cond = cond
-        self.stmts = stmts
+        self.stmts = stmts.copy()
 
 class LuaRepeat:
-    def __init__(self, stmts, cond):
-        self.stmts = stmts
+    def __init__(self, cond, stmts = []):
+        self.stmts = stmts.copy()
         self.cond = cond
 
 class LuaIf:
@@ -47,10 +47,10 @@ def __init__(self, branches):
         self.branches = branches
 
 class LuaIfBranch:
-    def __init__(self, cond, is_else, stmts):
+    def __init__(self, cond, is_else, stmts = []):
         self.cond = cond
         self.is_else = is_else
-        self.stmts = stmts
+        self.stmts = stmts.copy()
 
 class LuaBlock:
     def __init__(self, stmts = []):
diff --git a/bsc/sema.py b/bsc/sema.py
index 973c6d2..eeeb1d5 100644
--- a/bsc/sema.py
+++ b/bsc/sema.py
@@ -194,6 +194,11 @@ def check_stmt(self, stmt):
             self.check_const_decl(stmt)
         elif isinstance(stmt, VarDecl):
             self.check_var_decl(stmt)
+        elif isinstance(stmt, WhileStmt):
+            if not self.first_pass:
+                if self.check_expr(stmt.cond) != self.ctx.bool_type:
+                    report.error("non-boolean `while` condition", stmt.cond.pos)
+            self.check_stmts(stmt.stmts)
 
     ## === Expressions ==================================