diff --git a/INSTALL b/INSTALL
index 805fcb8..68462db 100644
--- a/INSTALL
+++ b/INSTALL
@@ -38,7 +38,8 @@ Prerequisites
 - Imlib2 requires the X11/Xlib.h header and links against some X11 libraries,
   at least on GNU/Linux with X11 GUI, thus X11 shared libraries and development
   headers are required for ssocr, too, although ssocr does not use X11 itself
-- Build tools, e.g., build-essential on a Debian (or Ubuntu) system.
+- Build tools, e.g., build-essential on a Debian (or Ubuntu) system, usually
+  contain both make and a C compiler.
 - To build a .deb package, you probably need the debhelper package.
 - To create an HTML version of the man page, you need a man utility that can
   produce HTML output.