diff --git a/iscsi-scst/usr/Makefile b/iscsi-scst/usr/Makefile
index 0ce5f815e..7356ffab8 100644
--- a/iscsi-scst/usr/Makefile
+++ b/iscsi-scst/usr/Makefile
@@ -22,7 +22,7 @@ SRCS_ADM = iscsi_adm.c param.c
 OBJS_ADM = $(SRCS_ADM:.c=.o)
 
 CFLAGS += -O2 -fno-inline -Wall -Wextra -Wstrict-prototypes -Wno-sign-compare \
-	-Werror=implicit-function-declaration -Wno-unused-parameter \
+	-Wimplicit-function-declaration -Wno-unused-parameter \
 	-Wno-missing-field-initializers -g -I../include
 CFLAGS += -D_GNU_SOURCE # required for glibc >= 2.8
 
diff --git a/scst/include/scst_sgv.h b/scst/include/scst_sgv.h
index 01bcd75c7..c09d0c9c7 100644
--- a/scst/include/scst_sgv.h
+++ b/scst/include/scst_sgv.h
@@ -17,6 +17,8 @@
  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  *  GNU General Public License for more details.
  */
+#ifndef __SCST_SGV_H
+#define __SCST_SGV_H
 
 /* SGV pool routines and flag bits */
 
@@ -67,3 +69,4 @@ void sgv_pool_free(struct sgv_pool_obj *sgv, struct scst_mem_lim *mem_lim);
 void *sgv_get_priv(struct sgv_pool_obj *sgv);
 
 void scst_init_mem_lim(struct scst_mem_lim *mem_lim);
+#endif /* ifndef __SCST_SGV_H */