diff --git a/GNUmakefile b/GNUmakefile
index a4450b0..c8323c1 100644
--- a/GNUmakefile
+++ b/GNUmakefile
@@ -15,7 +15,11 @@ buffer.a mmap.a taia.a tai.a dns.a case.a mult.a array.a io.a textcode.a
 all: t $(LIBS) libowfat.a
 
 CC=gcc
+ifneq ($(DEBUG),)
+CFLAGS=-pipe -Wall -g
+else
 CFLAGS=-pipe -Wall -O2 -fomit-frame-pointer
+endif
 #CFLAGS=-pipe -Os -march=pentiumpro -mcpu=pentiumpro -fomit-frame-pointer -fschedule-insns2 -Wall
 
 # startrip
diff --git a/io/io_canread.c b/io/io_canread.c
index 8c1a26c..bca6fd5 100644
--- a/io/io_canread.c
+++ b/io/io_canread.c
@@ -31,8 +31,9 @@ int64 io_canread() {
       e->next_read=alt_firstread;
       alt_firstread=r;
       debug_printf(("io_canread: enqueue %ld in alt read queue (next is %ld)\n",alt_firstread,e->next_read));
-#endif
+#else
       e->canread=0;
+#endif
       return r;
     }
   }
diff --git a/io/io_canwrite.c b/io/io_canwrite.c
index db294b3..67a0926 100644
--- a/io/io_canwrite.c
+++ b/io/io_canwrite.c
@@ -31,8 +31,9 @@ int64 io_canwrite() {
       e->next_write=alt_firstwrite;
       alt_firstwrite=r;
       debug_printf(("io_canwrite: enqueue %ld in alt write queue (next is %ld)\n",alt_firstwrite,e->next_write));
-#endif
+#else
       e->canwrite=0;
+#endif
       return r;
     }
   }