diff --git a/src/script_opt/Expr.cc b/src/script_opt/Expr.cc
index 3e8a71ce90..ca87c83bcf 100644
--- a/src/script_opt/Expr.cc
+++ b/src/script_opt/Expr.cc
@@ -894,7 +894,7 @@ bool AddToExpr::IsReduced(Reducer* c) const
 	if ( tag == TYPE_TABLE )
 		return op1->IsReduced(c) && op2->IsReduced(c);
 
-	if ( tag == TYPE_VECTOR && same_type(t, op2->GetType()) )
+	if ( tag == TYPE_VECTOR && IsVector(op2->GetType()->Tag()) && same_type(t, op2->GetType()) )
 		return op1->IsReduced(c) && op2->IsReduced(c);
 
 	return NonReduced(this);
@@ -923,7 +923,8 @@ ExprPtr AddToExpr::Reduce(Reducer* c, StmtPtr& red_stmt)
 
 			red_stmt = MergeStmts(red_stmt1, red_stmt2);
 
-			if ( tag == TYPE_VECTOR && ! same_type(t, op2->GetType()) )
+			if ( tag == TYPE_VECTOR &&
+			     (! IsVector(op2->GetType()->Tag()) || ! same_type(t, op2->GetType())) )
 				{
 				auto append = make_intrusive<AppendToExpr>(op1->Duplicate(), op2);
 				append->SetOriginal(ThisPtr());
diff --git a/src/script_opt/ZAM/Ops.in b/src/script_opt/ZAM/Ops.in
index 8051fe4b1f..2d555aaaee 100644
--- a/src/script_opt/ZAM/Ops.in
+++ b/src/script_opt/ZAM/Ops.in
@@ -402,7 +402,8 @@ eval	$1.re_val->AddTo(frame[z.v1].re_val, false);
 
 unary-op AddVecToVec
 op1-read
-eval	$1.vector_val->AddTo(frame[z.v1].vector_val, false);
+eval	if ( ! $1.vector_val->AddTo(frame[z.v1].vector_val, false) )
+		ZAM_run_time_error(z.loc, "incompatible vector element assignment");
 
 unary-op AddTableToTable
 op1-read
diff --git a/testing/btest/Baseline.zam/language.vector-any-append/.stderr b/testing/btest/Baseline.zam/language.vector-any-append/.stderr
new file mode 100644
index 0000000000..8e346e54f3
--- /dev/null
+++ b/testing/btest/Baseline.zam/language.vector-any-append/.stderr
@@ -0,0 +1,2 @@
+### BTest baseline data generated by btest-diff. Do not edit. Use "btest -U/-u" to update. Requires BTest >= 0.63.
+runtime error in <...>/vector-any-append.zeek, line 63: incompatible vector element assignment
diff --git a/testing/btest/Baseline.zam/language.vector-any-append/out b/testing/btest/Baseline.zam/language.vector-any-append/out
new file mode 100644
index 0000000000..5345b03b2d
--- /dev/null
+++ b/testing/btest/Baseline.zam/language.vector-any-append/out
@@ -0,0 +1,6 @@
+### BTest baseline data generated by btest-diff. Do not edit. Use "btest -U/-u" to update. Requires BTest >= 0.63.
+[0, 1, 2, 3]
+[4, 0, 1, 2, 3]
+[1, 2, 3, [4, 5]], 4, count, count, vector of count
+[[r=r], [r=r], [s=s], [s=s]]
+[a, -3]