diff --git a/acinclude.m4 b/acinclude.m4
index 64699d632b..f80df55a31 100644
--- a/acinclude.m4
+++ b/acinclude.m4
@@ -90,6 +90,9 @@ AC_ARG_ENABLE(debug-pam,
 AC_ARG_ENABLE(optimize-pam,
 [  --disable-optimize-pam		disable optimization for compilation of the PAM code (defaults to enabled)],, enable_optimize_pam="yes"
 )
+AC_ARG_ENABLE(warnings,
+[  --enable-warnings			enable compilation warnings when building with gcc (defaults to disabled)],, enable_warnings="no"
+)
 
 
 enable_login="no"
diff --git a/src/cf/osconf.m4 b/src/cf/osconf.m4
index 1a5197dac9..0161f1f0df 100644
--- a/src/cf/osconf.m4
+++ b/src/cf/osconf.m4
@@ -1114,6 +1114,12 @@ else
   NO_STRIP_KRB=-ns
 fi
 
+if test "x$enable_warnings" = "xyes"; then
+  if test "x$GCC" = "xyes"; then
+    XCFLAGS="${XCFLAGS} -Wall -Wstrict-prototypes -Wold-style-definition"
+  fi
+fi
+
 AC_SUBST(CCXPG2)
 AC_SUBST(CCOBJ)
 AC_SUBST(AFSD_LIBS)