diff --git a/Makefile b/Makefile
index b8d6b31305..0705fc2d3f 100644
--- a/Makefile
+++ b/Makefile
@@ -2271,7 +2271,7 @@ perl_localedir_SQ = $(localedir_SQ)
 
 ifndef NO_PERL
 PERL_HEADER_TEMPLATE = perl/header_templates/fixed_prefix.template.pl
-PERL_DEFINES :=
+PERL_DEFINES =
 PERL_DEFINES += $(PERL_PATH_SQ)
 PERL_DEFINES += $(PERLLIB_EXTRA_SQ)
 PERL_DEFINES += $(perllibdir_SQ)