Energy security is one of the most intensely debated topics. Majority of papers treat the issue from the hydrocarbon market perspective, but this research focuses on the coal market broken into two specific market segments: heating and electricity production. Using the case of Poland as an example, we conduct a cointegration analysis between the coal and natural gas markets. The study uses monthly data from 2011 until the beginning of 2019. Our results show that the Polish electricity sector is more connected to the international coal market than it is to the natural gas market, while the heating sector, despite using insignificant quantities of imported coal, is more connected to the natural gas market. Hence, energy security—in its price dimension—in those two market segments differs. This situation has important policy implications. First, energy policy should take this difference into account, and second, such variation implies that different market tools should be used in those market segments.