Apparently wget outputs to stderr, so let's make sure we're checking both stderr and stdout.
diff --git a/nvm.sh b/nvm.sh
index 781f2b5..aa46581 100644
--- a/nvm.sh
+++ b/nvm.sh
@@ -449,7 +449,7 @@
       tmpdir="$NVM_DIR/src"
       local tmptarball
       tmptarball="$tmpdir/node-$VERSION.tar.gz"
-      if [ "`nvm_download -s -I "$NVM_NODEJS_ORG_MIRROR/$VERSION/node-$VERSION.tar.gz" -o - | \grep '200 OK'`" != '' ]; then
+      if [ "`nvm_download -s -I "$NVM_NODEJS_ORG_MIRROR/$VERSION/node-$VERSION.tar.gz" -o - 2>&1 | \grep '200 OK'`" != '' ]; then
         tarball="$NVM_NODEJS_ORG_MIRROR/$VERSION/node-$VERSION.tar.gz"
         sum=`nvm_download -s $NVM_NODEJS_ORG_MIRROR/$VERSION/SHASUMS.txt -o - | \grep node-$VERSION.tar.gz | \awk '{print $1}'`
       elif [ "`nvm_download -s -I "$NVM_NODEJS_ORG_MIRROR/node-$VERSION.tar.gz" -o - | \grep '200 OK'`" != '' ]; then