diff --git a/src/Expr.cc b/src/Expr.cc
index c9cbd10e34..457890bb9f 100644
--- a/src/Expr.cc
+++ b/src/Expr.cc
@@ -2488,19 +2488,28 @@ ValPtr AssignExpr::InitVal(const zeek::Type* t, ValPtr aggr) const
 
 		auto index = op1->InitVal(tt->GetIndices().get(), nullptr);
 
-		if ( ! same_type(*yt, *op2->GetType(), true) )
+		if ( yt->Tag() == TYPE_RECORD )
 			{
-			if ( yt->Tag() == TYPE_RECORD && op2->GetType()->Tag() == TYPE_RECORD )
+			if ( op2->GetType()->Tag() != TYPE_RECORD )
 				{
-				if ( ! record_promotion_compatible(yt->AsRecordType(),
-				                                   op2->GetType()->AsRecordType()) )
-					{
-					Error("type mismatch in table value initialization: "
-					      "incompatible record types");
-					return nullptr;
-					}
+				Error(util::fmt("type mismatch in table value initialization: "
+				                "assigning '%s' to table with values of type '%s'",
+				                type_name(op2->GetType()->Tag()), type_name(yt->Tag())));
+				return nullptr;
 				}
-			else
+
+			if ( ! same_type(*yt, *op2->GetType()) &&
+			     ! record_promotion_compatible(yt->AsRecordType(),
+			                                   op2->GetType()->AsRecordType()) )
+				{
+				Error("type mismatch in table value initialization: "
+				      "incompatible record types");
+				return nullptr;
+				}
+			}
+		else
+			{
+			if ( ! same_type(*yt, *op2->GetType(), true) )
 				{
 				Error(util::fmt("type mismatch in table value initialization: "
 				                "assigning '%s' to table with values of type '%s'",
@@ -4086,29 +4095,6 @@ InExpr::InExpr(ExprPtr arg_op1, ExprPtr arg_op2)
 			SetType(base_type(TYPE_BOOL));
 		}
 
-	else if ( op1->GetType()->Tag() == TYPE_RECORD )
-		{
-		if ( op2->GetType()->Tag() != TYPE_TABLE )
-			{
-			op2->GetType()->Error("table/set required");
-			SetError();
-			}
-
-		else
-			{
-			const auto& t1 = op1->GetType();
-			const auto& it = op2->GetType()->AsTableType()->GetIndices();
-
-			if ( ! same_type(t1, it) )
-				{
-				t1->Error("indexing mismatch", op2->GetType().get());
-				SetError();
-				}
-			else
-				SetType(base_type(TYPE_BOOL));
-			}
-		}
-
 	else if ( op1->GetType()->Tag() == TYPE_STRING &&
 		  op2->GetType()->Tag() == TYPE_STRING )
 		SetType(base_type(TYPE_BOOL));
diff --git a/src/Type.cc b/src/Type.cc
index eac80264e8..69fb6602e2 100644
--- a/src/Type.cc
+++ b/src/Type.cc
@@ -1586,11 +1586,8 @@ bool same_type(const Type& arg_t1, const Type& arg_t2,
 	     arg_t2.Tag() == TYPE_ANY )
 		return true;
 
-	auto t1 = flatten_type(&arg_t1);
-	auto t2 = flatten_type(&arg_t2);
-
-	if ( t1 == t2 )
-		return true;
+	auto t1 = &arg_t1;
+	auto t2 = &arg_t2;
 
 	if ( t1->Tag() != t2->Tag() )
 		{
diff --git a/testing/btest/Baseline/language.type-check-func-call/out b/testing/btest/Baseline/language.type-check-func-call/out
new file mode 100644
index 0000000000..07308933c1
--- /dev/null
+++ b/testing/btest/Baseline/language.type-check-func-call/out
@@ -0,0 +1,5 @@
+### BTest baseline data generated by btest-diff. Do not edit. Use "btest -U/-u" to update. Requires BTest >= 0.63.
+error in <...>/type-check-func-call.zeek, line 8 and <...>/type-check-func-call.zeek, line 21: type clash (set[string] and s)
+error in <...>/type-check-func-call.zeek, line 21 and <...>/type-check-func-call.zeek, line 8: type mismatch (s and set[string])
+error in <...>/type-check-func-call.zeek, line 21: argument type mismatch in function call (sort_set(s))
+warning in <...>/type-check-func-call.zeek, line 21: expression value ignored (sort_set(s))
diff --git a/testing/btest/Baseline/language.type-check-operator-in/out b/testing/btest/Baseline/language.type-check-operator-in/out
new file mode 100644
index 0000000000..68114462b3
--- /dev/null
+++ b/testing/btest/Baseline/language.type-check-operator-in/out
@@ -0,0 +1,8 @@
+### BTest baseline data generated by btest-diff. Do not edit. Use "btest -U/-u" to update. Requires BTest >= 0.63.
+error in int and <...>/type-check-operator-in.zeek, line 30: arithmetic mixed with non-arithmetic (int and myrec)
+error in <...>/type-check-operator-in.zeek, line 30 and int: type mismatch (myrec and int)
+error in <...>/type-check-operator-in.zeek, line 30: not an index type (myrec in asdf)
+error in <...>/type-check-operator-in.zeek, line 14 and <...>/type-check-operator-in.zeek, line 31: indexing mismatch (list of string,MyRec and myrec)
+error in <...>/type-check-operator-in.zeek, line 31: not an index type (myrec in string_records)
+error in <...>/type-check-operator-in.zeek, line 15 and <...>/type-check-operator-in.zeek, line 32: indexing mismatch (list of MyRec,string and myrec)
+error in <...>/type-check-operator-in.zeek, line 32: not an index type (myrec in record_strings)
diff --git a/testing/btest/language/type-check-func-call.zeek b/testing/btest/language/type-check-func-call.zeek
new file mode 100644
index 0000000000..f1951b4e1a
--- /dev/null
+++ b/testing/btest/language/type-check-func-call.zeek
@@ -0,0 +1,22 @@
+# @TEST-EXEC-FAIL: zeek -b %INPUT >out 2>&1
+# @TEST-EXEC: TEST_DIFF_CANONIFIER=$SCRIPTS/diff-remove-abspath btest-diff out
+
+# @TEST-DOC: Test for type-checking of function call arguments.
+
+global s: set[string, string];
+
+function sort_set(s: set[string]): vector of string
+	{
+	local v: vector of string = vector();
+
+	for ( e in s )
+		v += e;
+
+	sort(v, strcmp);
+	return v;
+	}
+
+add s["hi", "there"];
+# This sort_set call should warn about mismatched table/set types.
+sort_set(s);
+
diff --git a/testing/btest/language/type-check-operator-in.zeek b/testing/btest/language/type-check-operator-in.zeek
new file mode 100644
index 0000000000..d5f340320f
--- /dev/null
+++ b/testing/btest/language/type-check-operator-in.zeek
@@ -0,0 +1,32 @@
+# @TEST-EXEC-FAIL: zeek -b %INPUT >out 2>&1
+# @TEST-EXEC: TEST_DIFF_CANONIFIER=$SCRIPTS/diff-remove-abspath btest-diff out
+
+# @TEST-DOC: Test for type-checking of `in` operator.
+
+type MyRec: record {
+	a: count &default=1;
+};
+
+local myrec = MyRec();
+local strings: set[string] = set();
+local records: set[MyRec] = set();
+local string_counts: set[string, count] = set();
+local string_records: set[string, MyRec] = set();
+local record_strings: set[MyRec, string] = set();
+
+# These are all valid.
+["asdf"] in strings;
+["hi", 0] in string_counts;
+myrec in records;
+[myrec] in records;
+MyRec() in records;
+[$a = 2] in records;
+[MyRec()] in records;
+[[$a = 2]] in records;
+["hi", myrec] in string_records;
+
+# All below should fail type-checking.
+
+myrec in "asdf";
+myrec in string_records;
+myrec in record_strings;