diff -r af5d8e985502 -r 765ab1b672a3 jitcraft/SemanticAnalysis.cpp
--- a/jitcraft/SemanticAnalysis.cpp	Sun Jul 01 14:52:57 2012 -0700
+++ b/jitcraft/SemanticAnalysis.cpp	Sun Jul 01 16:36:39 2012 -0700
@@ -189,6 +189,28 @@
     return false;
 }
 
+static inline Type *
+TypeCheckBinary(TokenKind token, Type *left, Type *right)
+{
+    if (!left || !right)
+        return NULL;
+
+    if ((token >= TOK_PLUS && token <= TOK_SLASH) ||
+        (token >= TOK_ASSIGN_ADD && token <= TOK_ASSIGN_DIV))
+    {
+        // If either side is a float, the other side must be a float or int.
+        if (left->isFloat() || right->isFloat()) {
+            assert(left->isFloat() || left->isInt32());
+            assert(right->isFloat() || right->isInt32());
+            return left->isFloat() ? left : right;
+        }
+    }
+
+    assert(left->isInt32() && right->isInt32());
+    assert(!left->tag() && !right->tag());
+    return left;
+}
+
 void
 SemanticAnalysis::visit(Assignment *node)
 {
@@ -214,34 +236,21 @@
             node->setType(var->type());
     }
 
+    if (node->token() != TOK_ASSIGN)
+        assert(TypeCheckBinary(node->token(), node->type(), node->expression()->type()));
+
     assert(TypeCheckAssignment(node->type(), node->expression()->type()));
 }
 
-
 void
 SemanticAnalysis::visit(BinaryExpression *node)
 {
+    // :TODO: use Local
     Type *left = visitForLoad(node->left());
     Type *right = visitForLoad(node->right());
 
-    if (node->token() >= TOK_PLUS && node->token() <= TOK_SLASH) {
-        // Both sides must be primitive.
-        if (!left || !right)
-            return;
-
-        // If either side is a float, the other side must be a float or int.
-        if (left->isFloat() || right->isFloat()) {
-            assert(left->isFloat() || left->isInt32());
-            assert(right->isFloat() || right->isInt32());
-            node->setType(left->isFloat() ? left : right);
-            return;
-        }
-    }
-
-    // For now, assert everything else is integer and untagged.
-    assert(left->isInt32() && right->isInt32());
-    assert(!left->tag() && !right->tag());
-    node->setType(left);
+    Type *result = TypeCheckBinary(node->token(), left, right);
+    node->setType(result);
 }
 
 void
@@ -258,8 +267,8 @@
     loopDepth_++;
     if (node->scope())
         scope_ = node->scope();
-    if (node->declaration())
-        node->declaration()->accept(this);
+    if (node->initialization())
+        node->initialization()->accept(this);
     if (node->condition())
         visitForLoad(node->condition());
     if (node->update())