diff --git a/compiler.go b/compiler.go
index 40c68928..41d48193 100644
--- a/compiler.go
+++ b/compiler.go
@@ -2219,6 +2219,17 @@ func (c *Compiler) parseBinOp(frame *Frame, binop *ssa.BinOp) (llvm.Value, error
 		} else {
 			return llvm.Value{}, errors.New("todo: unknown basic type in binop: " + typ.String())
 		}
+	case *types.Interface:
+		switch binop.Op {
+		case token.EQL, token.NEQ: // ==, !=
+			result := c.builder.CreateCall(c.mod.NamedFunction("runtime.interfaceEqual"), []llvm.Value{x, y}, "")
+			if binop.Op == token.NEQ {
+				result = c.builder.CreateNot(result, "")
+			}
+			return result, nil
+		default:
+			return llvm.Value{}, errors.New("binop on interface: " + binop.Op.String())
+		}
 	case *types.Pointer:
 		switch binop.Op {
 		case token.EQL: // ==
diff --git a/src/runtime/interface.go b/src/runtime/interface.go
index 98d8f954..aaaa575d 100644
--- a/src/runtime/interface.go
+++ b/src/runtime/interface.go
@@ -58,3 +58,17 @@ func interfaceMethod(itf _interface, method uint16) *uint8 {
 		i++
 	}
 }
+
+// Return true iff both interfaces are equal.
+func interfaceEqual(x, y _interface) bool {
+	if x.typecode != y.typecode {
+		// Different dynamic type so always unequal.
+		return false
+	}
+	if x.typecode == 0 {
+		// Both interfaces are nil, so they are equal.
+		return true
+	}
+	// TODO: depends on reflection.
+	panic("unimplemented: interface equality")
+}