https://bugs.gentoo.org/969792

diff --git a/Makefile.PL b/Makefile.PL
index ff8f585..67e7371 100644
--- a/Makefile.PL
+++ b/Makefile.PL
@@ -74,6 +74,10 @@ if ( $^O =~ /Win32/i ) {
     push @check, '../lpng143';
     push @check, '../giflib-4.1.6/lib';
 }
+else {
+    # Needed to link math functions on POSIX
+    push @LIBS, '-lm';
+}
 
 # Look for libjpeg
 for my $incdir ( $jpeg_inc, @check ) {