diff --git a/kernel/dyninit.c b/kernel/dyninit.c
index 8bd0d37..c028501 100644
--- a/kernel/dyninit.c
+++ b/kernel/dyninit.c
@@ -48,7 +48,6 @@ additionally:
 /*extern struct DynS FAR Dyn;*/
 
 #ifndef __TURBOC__
-#include "init-dat.h"
 extern struct DynS DOSFAR ASM Dyn;
 #else
 extern struct DynS FAR ASM Dyn;
diff --git a/kernel/init-mod.h b/kernel/init-mod.h
index 8e3257a..f04e178 100644
--- a/kernel/init-mod.h
+++ b/kernel/init-mod.h
@@ -353,8 +353,13 @@ extern struct RelocationTable
 
 extern void FAR *DOSFAR ASM XMSDriverAddress;
 #define XMSDriverAddress DOSDATA(XMSDriverAddress)
+#ifdef __GNUC__
+extern VOID _EnableA20(VOID);
+extern VOID _DisableA20(VOID);
+#else
 extern VOID ASMPASCAL FAR _EnableA20(VOID);
 extern VOID ASMPASCAL FAR _DisableA20(VOID);
+#endif
 
 extern void FAR * ASMPASCAL DetectXMSDriver(VOID);
 extern int ASMPASCAL init_call_XMScall(void FAR * driverAddress, UWORD ax,
diff --git a/mkfiles/gcc.mak b/mkfiles/gcc.mak
index 88ac5d4..b5cd9be 100644
--- a/mkfiles/gcc.mak
+++ b/mkfiles/gcc.mak
@@ -36,7 +36,7 @@ LIBPLUS=
 LIBTERM=
 
 TINY=-mcmodel=tiny
-CFLAGST=-Os -fpack-struct -fcall-used-es -w -o $@
+CFLAGST=-Os -fno-strict-aliasing -fpack-struct -fcall-used-es -Wno-pointer-to-int-cast -Wno-pragmas -Wno-array-bounds -Werror -o $@
 CFLAGSC=
 
 #
@@ -44,16 +44,18 @@ CFLAGSC=
 #
 # -mcmodel=small small memory model (small code/small data)
 # -Os           -> favor code size over execution time in optimizations
+# -fno-strict-aliasing don't assume strict aliasing rules
 # -fleading-underscore underscores leading field for DOS compiler compat
 # -fno-common    no "common" variables, just BSS for uninitialized data
 # -fpack-struct pack structure members
 # -ffreestanding don't assume any headers
 # -fcall-used-es es clobbered in function calls
 # -mrtd         use stdcall calling convention
-# -w            disable warnings for now
+# -Wno-pointer-to-int-cast  do not warn about FP_OFF
+# -Wno-pragmas  do not warn about #pragma pack
 # -Werror       treat all warnings as errors
 
-ALLCFLAGS+=-I../hdr $(TARGETOPT) -mcmodel=small -fleading-underscore -fno-common -fpack-struct -ffreestanding -fcall-used-es -mrtd -w -Werror -Os
+ALLCFLAGS+=-I../hdr $(TARGETOPT) -mcmodel=small -fleading-underscore -fno-common -fpack-struct -ffreestanding -fcall-used-es -mrtd -Wno-pointer-to-int-cast -Wno-pragmas -Werror -Os -fno-strict-aliasing
 INITCFLAGS=$(ALLCFLAGS) -o $@
 CFLAGS=$(ALLCFLAGS) -o $@
 
diff --git a/sys/sys.c b/sys/sys.c
index a68c9f0..c9cbc92 100644
--- a/sys/sys.c
+++ b/sys/sys.c
@@ -1128,7 +1128,7 @@ int generic_block_ioctl(unsigned drive, unsigned cx, unsigned char *par);
 
 #ifndef __TURBOC__
 
-int2526readwrite(int DosDrive, void *diskReadPacket, unsigned intno)
+int int2526readwrite(int DosDrive, void *diskReadPacket, unsigned intno)
 {
   union REGS regs;