linearize.c | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/linearize.c b/linearize.c
index 0250c6bb..b1a18219 100644
--- a/linearize.c
+++ b/linearize.c
@@ -2520,6 +2520,25 @@ static void check_tainted_insn(struct instruction *insn)
 	}
 }
 
+static void check_zero_extend(struct instruction *insn)
+{
+	struct instruction *def;
+	pseudo_t src = insn->src1;
+
+	if (src->type != PSEUDO_REG)
+		return;
+	def = src->def;
+	if (!def)
+		return;
+	switch (def->opcode) {
+	case OP_NEG: case OP_NOT:
+		warning(insn->pos, "zero-extending a negation - upper bits not negated");
+		break;
+	default:
+		break;
+	}
+}
+
 ///
 // issue warnings after all possible DCE
 static void late_warnings(struct entrypoint *ep)
@@ -2537,6 +2556,10 @@ static void late_warnings(struct entrypoint *ep)
 				// Check for illegal offsets.
 				check_access(insn);
 				break;
+			case OP_ZEXT:
+				// Check for missing sign extension..
+				check_zero_extend(insn);
+				break;
 			}
 		} END_FOR_EACH_PTR(insn);
 	} END_FOR_EACH_PTR(bb);