diff --git a/README.md b/README.md
index a409106..2f00549 100644
--- a/README.md
+++ b/README.md
@@ -6,6 +6,13 @@ This is a process monitor and system monitor.
 
 Currently have full engines for Linux, FreeBSD, OpenBSD and MacOS.
 
+REQUIREMENTS:
+
+An installation of EFL (v1.19.0+). Remember to set your PKG_CONFIG_PATH environment
+variable accordingly. For example if EFL is installed in /opt:
+
+export PKG_CONFIG_PATH="$PKG_CONFIG_PATH:/opt/libdata/pkgconfig"
+
 BUILD:
 
 $ make (or gmake)