diff --git a/pkg/eval/builtin_special.go b/pkg/eval/builtin_special.go
index 00f6bb56..3630cdbc 100644
--- a/pkg/eval/builtin_special.go
+++ b/pkg/eval/builtin_special.go
@@ -90,7 +90,7 @@ func compileVar(cp *compiler, fn *parse.Form) effectOp {
 		}
 
 		name := pn.Value
-		if strings.Contains(name, NsSuffix) {
+		if !IsUnqualified(name) {
 			cp.errorpf(cn, "variable declared in var must be unqualified")
 		}
 		sigil, name := SplitSigil(name)
@@ -108,6 +108,12 @@ func compileVar(cp *compiler, fn *parse.Form) effectOp {
 	return nopOp{}
 }
 
+// IsUnqualified returns whether name is an unqualified variable name.
+func IsUnqualified(name string) bool {
+	i := strings.IndexByte(name, ':')
+	return i == -1 || i == len(name)-1
+}
+
 // SetForm = 'set' { LHS } '=' { Compound }
 func compileSet(cp *compiler, fn *parse.Form) effectOp {
 	eq := -1
diff --git a/pkg/eval/builtin_special_test.go b/pkg/eval/builtin_special_test.go
index 4c034a6b..44889cf4 100644
--- a/pkg/eval/builtin_special_test.go
+++ b/pkg/eval/builtin_special_test.go
@@ -20,6 +20,8 @@ func TestVar(t *testing.T) {
 		That("var x", "put $x").Puts(nil),
 		// Declaring one variable whose name needs to be quoted
 		That("var 'a/b'", "put $'a/b'").Puts(nil),
+		// Declaring one variable whose name ends in ":".
+		That("var a:").DoesNothing(),
 		// Declaring multiple variables
 		That("var x y", "put $x $y").Puts(nil, nil),
 		// Declaring one variable with initial value