diff --git a/pkgs/development/libraries/libxml2/setup-hook.sh b/pkgs/development/libraries/libxml2/setup-hook.sh
index 112dbe0c5136..4ab0dadd8b29 100644
--- a/pkgs/development/libraries/libxml2/setup-hook.sh
+++ b/pkgs/development/libraries/libxml2/setup-hook.sh
@@ -11,14 +11,6 @@ addXMLCatalogs () {
 if test -z "$libxmlHookDone"; then
     libxmlHookDone=1
 
-    # Set http_proxy and ftp_proxy to an invalid host to prevent
-    # xmllint and xsltproc from trying to download DTDs from the
-    # network even when --nonet is not given.  That would be impure.
-    # (Note that .invalid is a reserved domain guaranteed not to
-    # work.)
-    export http_proxy=http://nodtd.invalid/
-    export ftp_proxy=http://nodtd.invalid/
-
     # Set up XML_CATALOG_FILES.  An empty initial value prevents
     # xmllint and xsltproc from looking in /etc/xml/catalog.
     export XML_CATALOG_FILES
diff --git a/pkgs/tools/text/sgml/opensp/setup-hook.sh b/pkgs/tools/text/sgml/opensp/setup-hook.sh
index 2c9142da1016..72751b85ef60 100644
--- a/pkgs/tools/text/sgml/opensp/setup-hook.sh
+++ b/pkgs/tools/text/sgml/opensp/setup-hook.sh
@@ -9,14 +9,6 @@ addSGMLCatalogs () {
 if test -z "$sgmlHookDone"; then
     sgmlHookDone=1
 
-    # Set http_proxy and ftp_proxy to a invalid host to prevent
-    # xmllint and xsltproc from trying to download DTDs from the
-    # network even when --nonet is not given.  That would be impure.
-    # (Note that .invalid is a reserved domain guaranteed not to
-    # work.)
-    export http_proxy=http://nodtd.invalid/
-    export ftp_proxy=http://nodtd.invalid/
-
     export SGML_CATALOG_FILES
     envHooks=(${envHooks[@]} addSGMLCatalogs)
 fi