diff --git a/doc/install-source.html b/doc/install-source.html
index d9157c2b17..9a817676c1 100644
--- a/doc/install-source.html
+++ b/doc/install-source.html
@@ -33,7 +33,7 @@ compiler using the GCC back end, see
 </p>
 
 <p>
-The Go compilers support five instruction sets.
+The Go compilers support six instruction sets.
 There are important differences in the quality of the compilers for the different
 architectures.
 </p>