diff --git a/pkg/corset/compiler/translator.go b/pkg/corset/compiler/translator.go
index f0a7a447e..e98b2ccdb 100644
--- a/pkg/corset/compiler/translator.go
+++ b/pkg/corset/compiler/translator.go
@@ -389,7 +389,10 @@ func (t *translator) translateDefLookup(decl *ast.DefLookup) []SyntaxError {
 func (t *translator) translateDefLookupSources(selector ast.Expr,
 	sources []ast.Expr) (lookup.Vector[mir.Term], ast.Context, []SyntaxError) {
 	// Determine context of ith set of targets
-	context, j := ast.ContextOfExpressions(sources...)
+	var (
+		context, j = ast.ContextOfExpressions(sources...)
+		vector     lookup.Vector[mir.Term]
+	)
 	// Include selector (when present)
 	if selector != nil {
 		context = context.Join(selector.Context())
@@ -408,10 +411,51 @@ func (t *translator) translateDefLookupSources(selector ast.Expr,
 		s, errs := t.translateExpression(selector, module, 0)
 		errors = append(errors, errs...)
 
-		return lookup.FilteredVector(module.Id(), s, terms...), context, errors
+		vector = lookup.FilteredVector(module.Id(), s, terms...)
+	} else {
+		vector = lookup.UnfilteredVector(module.Id(), terms...)
 	}
+	// Sanity check vector
+	errors = append(errors, t.checkLookupVector(vector, selector, sources)...)
+	//
+	return vector, context, errors
+}
+
+func (t *translator) checkLookupVector(vector lookup.Vector[mir.Term], selector ast.Expr,
+	terms []ast.Expr) []SyntaxError {
 	//
-	return lookup.UnfilteredVector(module.Id(), terms...), context, errors
+	var (
+		modmap = t.schema.Module(vector.Module)
+		errors []SyntaxError
+	)
+	// Look for any negative terms
+	for i, ith := range vector.Terms {
+		// Determine value range of ith term
+		valrange := ith.ValueRange(modmap)
+		// Determine bitwidth for that range
+		_, signed := valrange.BitWidth()
+		// Sanity check signed lookups
+		if signed {
+			errors = append(errors, *t.srcmap.SyntaxError(terms[i], "signed term encountered"))
+		}
+	}
+	// Check selector is binary
+	if vector.HasSelector() {
+		// Determine value range of ith term
+		valrange := vector.Selector.Unwrap().ValueRange(modmap)
+		// Determine bitwidth for that range
+		bitwidth, signed := valrange.BitWidth()
+		// Check for signed selector
+		if signed {
+			errors = append(errors, *t.srcmap.SyntaxError(selector, "signed selector encountered"))
+		}
+		// Check for non-binary selector
+		if bitwidth > 1 {
+			errors = append(errors, *t.srcmap.SyntaxError(selector, "non-binary selector encountered"))
+		}
+	}
+	// Done
+	return errors
 }
 
 // Translate a "definrange" declaration.
diff --git a/pkg/test/invalid_corset_test.go b/pkg/test/invalid_corset_test.go
index 1c1112ed0..29fb6e9fd 100644
--- a/pkg/test/invalid_corset_test.go
+++ b/pkg/test/invalid_corset_test.go
@@ -480,6 +480,19 @@ func Test_Invalid_Lookup_10(t *testing.T) {
 	CheckInvalid(t, "invalid/lookup_invalid_10")
 }
 
+func Test_Invalid_Lookup_11(t *testing.T) {
+	CheckInvalid(t, "invalid/lookup_invalid_11")
+}
+func Test_Invalid_Lookup_12(t *testing.T) {
+	CheckInvalid(t, "invalid/lookup_invalid_12")
+}
+func Test_Invalid_Lookup_13(t *testing.T) {
+	CheckInvalid(t, "invalid/lookup_invalid_13")
+}
+func Test_Invalid_Lookup_14(t *testing.T) {
+	CheckInvalid(t, "invalid/lookup_invalid_14")
+}
+
 // ===================================================================
 // Interleavings
 // ===================================================================
diff --git a/testdata/invalid/lookup_invalid_11.lisp b/testdata/invalid/lookup_invalid_11.lisp
new file mode 100644
index 000000000..6876eff2e
--- /dev/null
+++ b/testdata/invalid/lookup_invalid_11.lisp
@@ -0,0 +1,3 @@
+;;error:3:16-23:signed term encountered
+(defcolumns (X :u16) (Y :u16))
+(deflookup l1 ((- 1 X)) (Y))
diff --git a/testdata/invalid/lookup_invalid_12.lisp b/testdata/invalid/lookup_invalid_12.lisp
new file mode 100644
index 000000000..e88e1dce0
--- /dev/null
+++ b/testdata/invalid/lookup_invalid_12.lisp
@@ -0,0 +1,3 @@
+;;error:3:20-27:signed term encountered
+(defcolumns (X :u16) (Y :u16))
+(deflookup l1 (X) ((- 1 Y)))
diff --git a/testdata/invalid/lookup_invalid_13.lisp b/testdata/invalid/lookup_invalid_13.lisp
new file mode 100644
index 000000000..180e2190f
--- /dev/null
+++ b/testdata/invalid/lookup_invalid_13.lisp
@@ -0,0 +1,3 @@
+;;error:3:20-27:signed selector encountered
+(defcolumns (P :u1) (X :u16) (Y :u16))
+(defclookup l1 (X) (- 0 P) (Y))
diff --git a/testdata/invalid/lookup_invalid_14.lisp b/testdata/invalid/lookup_invalid_14.lisp
new file mode 100644
index 000000000..49ae13430
--- /dev/null
+++ b/testdata/invalid/lookup_invalid_14.lisp
@@ -0,0 +1,3 @@
+;;error:3:20-21:non-binary selector encountered
+(defcolumns (P :u2) (X :u16) (Y :u16))
+(defclookup l1 (X) P (Y))