diff --git a/src/ld65/error.h b/src/ld65/error.h
index 9f213abe2..2ce1c8601 100644
--- a/src/ld65/error.h
+++ b/src/ld65/error.h
@@ -38,6 +38,11 @@
 
 
 
+/* common */
+#include "attrib.h"
+
+
+
 /*****************************************************************************/
 /*	  		   	     Data		     		     */
 /*****************************************************************************/
@@ -57,13 +62,13 @@ extern const char _MsgFail [];
 
 
 
-void Warning (const char* Format, ...);
+void Warning (const char* Format, ...) attribute((format(printf,1,2)));
 /* Print a warning message */
 
-void Error (const char* Format, ...);
+void Error (const char* Format, ...) attribute((format(printf,1,2)));
 /* Print an error message and die */
 
-void Internal (const char* Format, ...);
+void Internal (const char* Format, ...) attribute((format(printf,1,2)));
 /* Print an internal error message and die */
 
 #define CHECK(c)     							\
diff --git a/src/ld65/expr.c b/src/ld65/expr.c
index 4122e5681..ed65a991c 100644
--- a/src/ld65/expr.c
+++ b/src/ld65/expr.c
@@ -33,9 +33,11 @@
 
 
 
-#include "../common/exprdefs.h"
-#include "../common/xmalloc.h"
-
+/* common */
+#include "exprdefs.h"
+#include "xmalloc.h"
+	  
+/* ld65 */
 #include "global.h"
 #include "error.h"
 #include "fileio.h"
@@ -253,7 +255,7 @@ int IsConstExpr (ExprNode* Root)
 		 * which in turn means, that we have a circular reference.
 		 */
 		if (ExportHasMark (E)) {
-		    Error ("Circular reference for symbol `%s', %s(%u)",
+		    Error ("Circular reference for symbol `%s', %s(%lu)",
 			   E->Name, E->Obj->Files [E->Pos.Name], E->Pos.Line);
 		    Const = 0;
 		} else {
diff --git a/src/ld65/make/gcc.mak b/src/ld65/make/gcc.mak
index 8423a059c..b0be2f660 100644
--- a/src/ld65/make/gcc.mak
+++ b/src/ld65/make/gcc.mak
@@ -4,7 +4,7 @@
 
 # Default for the compiler lib search path as compiler define
 CDEFS=-DCC65_LIB=\"/usr/lib/cc65/lib/\"
-CFLAGS = -g -O2 -Wall $(CDEFS)
+CFLAGS = -g -O2 -Wall -I../common $(CDEFS)
 CC=gcc
 LDFLAGS=