diff --git a/install.sh b/install.sh
index 77f7f31..d47c57d 100755
--- a/install.sh
+++ b/install.sh
@@ -327,10 +327,10 @@ nvm_do_install() {
   local PROFILE_INSTALL_DIR
   PROFILE_INSTALL_DIR="$(nvm_install_dir | command sed "s:^$HOME:\$HOME:")"
 
-  SOURCE_STR="\\nexport NVM_DIR=\"${PROFILE_INSTALL_DIR}\"\\n[ -s \"\$NVM_DIR/nvm.sh\" ] && \\. \"\$NVM_DIR/nvm.sh\"  # This loads nvm\\n"
+  SOURCE_STR="\\nexport NVM_DIR=\"${PROFILE_INSTALL_DIR}\"\\n[ ! -s \"\$NVM_DIR/nvm.sh\" ] || \\. \"\$NVM_DIR/nvm.sh\"  # This loads nvm\\n"
 
   # shellcheck disable=SC2016
-  COMPLETION_STR='[ -s "$NVM_DIR/bash_completion" ] && \. "$NVM_DIR/bash_completion"  # This loads nvm bash_completion\n'
+  COMPLETION_STR='[ ! -s "$NVM_DIR/bash_completion" ] || \. "$NVM_DIR/bash_completion"  # This loads nvm bash_completion\n'
   BASH_OR_ZSH=false
 
   if [ -z "${NVM_PROFILE-}" ] ; then