diff --git a/Makefile.am b/Makefile.am
index 9d349c2..1c915f1 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -4,7 +4,7 @@
 WARN_CLANG=-Wformat-nonliteral -Wstrncat-size -Wformat-security -Wsign-conversion -Wconversion -Wfloat-conversion -Wshorten-64-to-32 -Wuninitialized -Wmissing-variable-declarations  -Wmissing-declarations
 WARN_GCC=-Wformat=2 -Wformat-overflow=2 -Wformat-nonliteral -Wformat-truncation=2 -Wnull-dereference -Wstrict-overflow=2 -Wstringop-overflow=4 -Walloca-larger-than=4096 -Wtype-limits -Wconversion -Wtrampolines -Wstrict-prototypes -Wmissing-prototypes -Wmissing-declarations -fno-common -Wcast-align
 CFLAGS ?= -g
-OPTS=-I. -O3 $(CFLAGS) -fcommon
+OPTS=-I. -O3 $(CFLAGS) -fcommon -Wl,--allow-multiple-definition
 # -Wall -g -pedantic
 LIBS=-lm
 DESTDIR ?=
diff --git a/hydra-gtk/Makefile.in b/hydra-gtk/Makefile.in
index 4085f85..c29f5fa 100644
--- a/hydra-gtk/Makefile.in
+++ b/hydra-gtk/Makefile.in
@@ -62,7 +62,8 @@ MAINT = @MAINT@
 MAKEINFO = @MAKEINFO@
 PACKAGE = @PACKAGE@
 PACKAGE_CFLAGS = @PACKAGE_CFLAGS@ -fcommon -Wl,--allow-multiple-definition
-PACKAGE_LIBS = @PACKAGE_LIBS@
+PACKAGE_LDFLAGS = -fcommon -Wl,--allow-multiple-definition
+PACKAGE_LIBS = -fcommon -Wl,--allow-multiple-definition @PACKAGE_LIBS@
 PKG_CONFIG = @PKG_CONFIG@
 VERSION = @VERSION@
 
diff --git a/hydra-gtk/src/Makefile.in b/hydra-gtk/src/Makefile.in
index d2ff022..1ed2b96 100644
--- a/hydra-gtk/src/Makefile.in
+++ b/hydra-gtk/src/Makefile.in
@@ -62,7 +62,7 @@ MAINT = @MAINT@
 MAKEINFO = @MAKEINFO@
 PACKAGE = @PACKAGE@
 PACKAGE_CFLAGS = @PACKAGE_CFLAGS@ -fcommon -Wl,--allow-multiple-definition
-PACKAGE_LIBS = @PACKAGE_LIBS@
+PACKAGE_LIBS = -fcommon -Wl,--allow-multiple-definition @PACKAGE_LIBS@
 PKG_CONFIG = @PKG_CONFIG@
 VERSION = @VERSION@
 
diff --git a/hydra-gtk/src/main.c b/hydra-gtk/src/main.c
index 03c5f21..72d6dd7 100644
--- a/hydra-gtk/src/main.c
+++ b/hydra-gtk/src/main.c
@@ -18,8 +18,11 @@ char *hydra_path1 = "./hydra";
 char *hydra_path2 = "/usr/local/bin/hydra";
 char *hydra_path3 = "/usr/bin/hydra";
 
+GtkWidget *wndMain;
+char *HYDRA_BIN;
+guint message_id;
+
 int main(int argc, char *argv[]) {
-  extern GtkWidget *wndMain;
   int i;
   extern guint message_id;
   GtkWidget *output;
diff --git a/hydra-gtk/src/support.h b/hydra-gtk/src/support.h
index bd88545..f1f7bbb 100644
--- a/hydra-gtk/src/support.h
+++ b/hydra-gtk/src/support.h
@@ -37,6 +37,6 @@ GdkPixbuf *create_pixbuf(const gchar *filename);
 /* This is used to set ATK action descriptions. */
 void glade_set_atk_action_description(AtkAction *action, const gchar *action_name, const gchar *description);
 
-GtkWidget *wndMain;
-char *HYDRA_BIN;
-guint message_id;
+extern GtkWidget *wndMain;
+extern char *HYDRA_BIN;
+extern guint message_id;