diff --git a/jetty-http/src/main/resources/org/eclipse/jetty/http/mime.properties b/jetty-http/src/main/resources/org/eclipse/jetty/http/mime.properties
index 654454c7a14..302cbd0a0b5 100644
--- a/jetty-http/src/main/resources/org/eclipse/jetty/http/mime.properties
+++ b/jetty-http/src/main/resources/org/eclipse/jetty/http/mime.properties
@@ -12,6 +12,7 @@ bcpio=application/x-bcpio
 bin=application/octet-stream
 cab=application/x-cabinet
 cdf=application/x-netcdf
+chm=application/vnd.ms-htmlhelp
 class=application/java-vm
 cpio=application/x-cpio
 cpt=application/mac-compactpro