diff --git a/install.sh b/install.sh
index 2cae3a2e..796b7557 100755
--- a/install.sh
+++ b/install.sh
@@ -490,6 +490,9 @@ nvm_do_install() {
     # shellcheck disable=SC2016
     if ${BASH_OR_ZSH} && ! command grep -qc '$NVM_DIR/bash_completion' "$NVM_PROFILE"; then
       nvm_echo "=> Appending bash_completion source string to $NVM_PROFILE"
+      if [ -n "$(command tail -c 1 "$NVM_PROFILE")" ]; then
+        nvm_echo >> "$NVM_PROFILE"
+      fi
       command printf '%b' "$COMPLETION_STR" >> "$NVM_PROFILE"
     else
       nvm_echo "=> bash_completion source string already in ${NVM_PROFILE}"
diff --git a/test/install_script/nvm_do_install_profile_without_trailing_newline b/test/install_script/nvm_do_install_profile_without_trailing_newline
new file mode 100755
index 00000000..4c5be69f
--- /dev/null
+++ b/test/install_script/nvm_do_install_profile_without_trailing_newline
@@ -0,0 +1,65 @@
+#!/bin/sh
+
+die () { echo "$@" ; cleanup ; exit 1; }
+
+cleanup() {
+  unset -f install_nvm_from_git install_nvm_as_script nvm_detect_profile nvm_has
+  unset -f nvm_check_global_modules nvm_install_node
+  unset -f setup cleanup die assert_profile
+  unset NVM_ENV METHOD PROFILE
+  rm -rf "${TMPDIR_FOR_TEST-}" 2>/dev/null
+}
+
+setup() {
+  NVM_ENV=testing \. ../../install.sh
+
+  # Mock installation functions to do nothing
+  install_nvm_from_git() { :; }
+  install_nvm_as_script() { :; }
+  nvm_check_global_modules() { :; }
+  nvm_install_node() { :; }
+
+  # Mock nvm_has to return true for git
+  nvm_has() {
+    case "$1" in
+      git) return 0 ;;
+      xcode-select) return 1 ;;
+      *) return 1 ;;
+    esac
+  }
+}
+
+setup
+
+TMPDIR_FOR_TEST="$(mktemp -d)"
+TEST_PROFILE="${TMPDIR_FOR_TEST}/.bashrc"
+EXPECTED_PROFILE="${TMPDIR_FOR_TEST}/expected"
+COMPLETION_LINE='[ -s "$NVM_DIR/bash_completion" ] && \. "$NVM_DIR/bash_completion"  # This loads nvm bash_completion'
+
+# runs the installer against $TEST_PROFILE, and compares the whole file, byte for byte, with $EXPECTED_PROFILE.
+# `nvm_do_install` unsets every `nvm_` function when it finishes, so each run sources the installer and mocks afresh.
+assert_profile() {
+  setup
+  nvm_detect_profile() {
+    echo "${TEST_PROFILE}"
+  }
+  PROFILE='' METHOD='' NVM_DIR="$(cd ../.. && pwd)" nvm_do_install > /dev/null 2>&1
+  command cmp -s "${TEST_PROFILE}" "${EXPECTED_PROFILE}" || die "$1; got: >$(command cat "${TEST_PROFILE}")<"
+}
+
+#
+# Test: when the profile already sources nvm.sh but does not end with a newline,
+# the bash_completion line must be appended on its own line, and the profile must end with a newline
+#
+command printf '%s\n%s' '. "$HOME/.nvm/nvm.sh"' "alias ll='ls -l'" > "${TEST_PROFILE}"
+command printf '%s\n%s\n%s\n' '. "$HOME/.nvm/nvm.sh"' "alias ll='ls -l'" "${COMPLETION_LINE}" > "${EXPECTED_PROFILE}"
+assert_profile 'bash_completion line was not appended on its own line, ending with a newline'
+
+#
+# Test: when the profile already ends with a newline, no blank line is added before the bash_completion line
+#
+command printf '%s\n%s\n' '. "$HOME/.nvm/nvm.sh"' "alias ll='ls -l'" > "${TEST_PROFILE}"
+command printf '%s\n%s\n%s\n' '. "$HOME/.nvm/nvm.sh"' "alias ll='ls -l'" "${COMPLETION_LINE}" > "${EXPECTED_PROFILE}"
+assert_profile 'a profile ending with a newline got an extra blank line before the bash_completion line'
+
+cleanup