diff --git a/src/occBootLoader/img_defs.mk b/src/occBootLoader/img_defs.mk
index a53d9db1..fe8859d1 100644
--- a/src/occBootLoader/img_defs.mk
+++ b/src/occBootLoader/img_defs.mk
@@ -5,7 +5,7 @@
 #
 # OpenPOWER OnChipController Project
 #
-# Contributors Listed Below - COPYRIGHT 2015,2016
+# Contributors Listed Below - COPYRIGHT 2015,2017
 # [+] International Business Machines Corp.
 #
 #
@@ -226,7 +226,7 @@ PIPE-CFLAGS = -pipe -Wa,-m405
 GCC-CFLAGS += -g -Wall -fsigned-char -msoft-float  \
 	-m32 -mbig-endian -mcpu=405 -mmultiple -mstring \
 	-meabi -msdata=eabi -ffreestanding -fno-common \
-	-fno-inline-functions-called-once
+	-fno-inline-functions-called-once -std=gnu89
 
 CFLAGS      =  -c $(GCC-CFLAGS) $(PIPE-CFLAGS) $(GCC-O-LEVEL) $(INCLUDES)
 
diff --git a/src/occ_405/img_defs.mk b/src/occ_405/img_defs.mk
index 9dea1ebe..d0176c28 100644
--- a/src/occ_405/img_defs.mk
+++ b/src/occ_405/img_defs.mk
@@ -5,7 +5,7 @@
 #
 # OpenPOWER OnChipController Project
 #
-# Contributors Listed Below - COPYRIGHT 2015,2016
+# Contributors Listed Below - COPYRIGHT 2015,2017
 # [+] International Business Machines Corp.
 #
 #
@@ -253,7 +253,7 @@ PIPE-CFLAGS = -pipe -Wa,-m405
 GCC-CFLAGS += -g -Wall -fsigned-char -msoft-float  \
 	-m32 -mbig-endian -mcpu=405 -mmultiple -mstring \
 	-meabi -msdata=eabi -ffreestanding -fno-common \
-	-fno-inline-functions-called-once
+	-fno-inline-functions-called-once -std=gnu89
 
 CFLAGS      =  -c $(GCC-CFLAGS) $(PIPE-CFLAGS) $(GCC-O-LEVEL) $(INCLUDES)
 
diff --git a/src/occ_gpe0/img_defs.mk b/src/occ_gpe0/img_defs.mk
index 0a315076..f722193a 100644
--- a/src/occ_gpe0/img_defs.mk
+++ b/src/occ_gpe0/img_defs.mk
@@ -5,7 +5,7 @@
 #
 # OpenPOWER OnChipController Project
 #
-# Contributors Listed Below - COPYRIGHT 2015,2016
+# Contributors Listed Below - COPYRIGHT 2015,2017
 # [+] International Business Machines Corp.
 #
 #
@@ -222,7 +222,8 @@ GCC-CFLAGS += -Wall -fsigned-char -msoft-float  \
     -ffixed-r22 -ffixed-r23 -ffixed-r24 -ffixed-r25 \
     -ffixed-r26 -ffixed-r27 \
     -ffixed-cr1 -ffixed-cr2 -ffixed-cr3 -ffixed-cr4 \
-    -ffixed-cr5 -ffixed-cr6 -ffixed-cr7 -Werror
+    -ffixed-cr5 -ffixed-cr6 -ffixed-cr7 -Werror \
+    -std=gnu89
 
 else
 PIPE-CFLAGS = -pipe
@@ -238,6 +239,7 @@ GCC-CFLAGS += -meabi
 GCC-CFLAGS += -ffreestanding
 GCC-CFLAGS += -fno-common
 GCC-CFLAGS += -fno-inline-functions-called-once
+GCC-CFLAGS += -std=gnu89
 endif
 
 CFLAGS      =  -c $(GCC-CFLAGS) $(PIPE-CFLAGS) $(GCC-O-LEVEL) $(INCLUDES)
diff --git a/src/occ_gpe1/img_defs.mk b/src/occ_gpe1/img_defs.mk
index 1f816274..ba8cc185 100644
--- a/src/occ_gpe1/img_defs.mk
+++ b/src/occ_gpe1/img_defs.mk
@@ -5,7 +5,7 @@
 #
 # OpenPOWER OnChipController Project
 #
-# Contributors Listed Below - COPYRIGHT 2015,2016
+# Contributors Listed Below - COPYRIGHT 2015,2017
 # [+] International Business Machines Corp.
 #
 #
@@ -222,7 +222,8 @@ GCC-CFLAGS += -Wall -fsigned-char -msoft-float  \
     -ffixed-r22 -ffixed-r23 -ffixed-r24 -ffixed-r25 \
     -ffixed-r26 -ffixed-r27 \
     -ffixed-cr1 -ffixed-cr2 -ffixed-cr3 -ffixed-cr4 \
-    -ffixed-cr5 -ffixed-cr6 -ffixed-cr7 -Werror
+    -ffixed-cr5 -ffixed-cr6 -ffixed-cr7 -Werror \
+    -std=gnu89
 
 else
 PIPE-CFLAGS = -pipe
@@ -238,6 +239,7 @@ GCC-CFLAGS += -meabi
 GCC-CFLAGS += -ffreestanding
 GCC-CFLAGS += -fno-common
 GCC-CFLAGS += -fno-inline-functions-called-once
+GCC-CFLAGS += -std=gnu89
 endif
 
 CFLAGS      =  -c $(GCC-CFLAGS) $(PIPE-CFLAGS) $(GCC-O-LEVEL) $(INCLUDES)