diff --git a/include/ruby/ruby.h b/include/ruby/ruby.h
index dd140c3476..77fb1afa8d 100644
--- a/include/ruby/ruby.h
+++ b/include/ruby/ruby.h
@@ -345,7 +345,7 @@ rb_long2int_inline(long n)
 
 #define IMMEDIATE_P(x) ((VALUE)(x) & IMMEDIATE_MASK)
 
-#define SYMBOL_P(x) (((VALUE)(x)&~(~(VALUE)0<<RUBY_SPECIAL_SHIFT))==SYMBOL_FLAG)
+#define SYMBOL_P(x) (((VALUE)(x)&~((~(VALUE)0)<<RUBY_SPECIAL_SHIFT))==SYMBOL_FLAG)
 #define ID2SYM(x) (((VALUE)(x)<<RUBY_SPECIAL_SHIFT)|SYMBOL_FLAG)
 #define SYM2ID(x) RSHIFT((unsigned long)(x),RUBY_SPECIAL_SHIFT)