diff --git a/core/vm/analysis.go b/core/vm/analysis.go
index fc7cc4fc153a6..74db95bd6fc3b 100644
--- a/core/vm/analysis.go
+++ b/core/vm/analysis.go
@@ -85,11 +85,11 @@ func codeBitmapInternal(code, bits bitvec) bitvec {
 				bits.set16(pc)
 				pc += 16
 				numbits -= 16
-			}
-			if numbits >= 16 {
-				bits.set16(pc)
-				pc += 16
-				numbits -= 16
+				if numbits == 16 {
+					bits.set16(pc)
+					pc += 16
+					numbits = 0
+				}
 			}
 			if numbits >= 8 {
 				bits.set8(pc)