diff --git a/source/basic.tex b/source/basic.tex
index b25702a164..06652f0d3b 100644
--- a/source/basic.tex
+++ b/source/basic.tex
@@ -1211,7 +1211,6 @@
 namespace B = A;
 namespace B = A;        // OK, no effect
 namespace B = B;        // OK, no effect
-namespace A = B;        // OK, no effect
 namespace B {}          // error: different entity for \tcode{B}
 
 void g() {