  Natural inflation is a well-motivated model for the early universe in which
an inflaton potential of the pseudo-Nambu-Goldstone form, $V(\phi) =
\Lambda^4[1 + \cos{(\phi/f)}]$, can naturally drive a cosmic accelerated epoch.
This paper investigates the observational viability of the minimally and
non-minimally coupled natural inflation scenarios in light of current Cosmic
Microwave Background (CMB) observations. We find that a small and negative
coupling of the field with gravity can alleviate the well-known observational
discrepancies of the minimally coupled model. We perform a Monte Carlo Markov
Chain analysis of the Planck 2018 CMB and BICEP/Keck Array B-mode polarization
data to estimate how strong the coupling $\xi$ should be to achieve concordance
with data. We also briefly discuss the impact of these results on the physical
interpretation of the natural inflation scenario.
