diff --git a/kernel/busses/i2c-isa.c b/kernel/busses/i2c-isa.c
index 061acb45..1a5daf91 100644
--- a/kernel/busses/i2c-isa.c
+++ b/kernel/busses/i2c-isa.c
@@ -78,7 +78,7 @@ int isa_master_xfer (struct isa_adapter *adap, struct i2c_msg msgs[],
   printk("isa.o: isa_master_xfer called for adapter `%s' "
          "(no i2c level access possible!)\n",
          adap->name);
-  return 0;
+  return -1;
 }
 
 /* Algorithm slave_send call-back implementation. Can't do that... */
@@ -87,7 +87,7 @@ int isa_slave_send (struct isa_adapter *adap, char *data, int len)
   printk("isa.o: isa_slave_send called for adapter `%s' "
          "(no i2c level access possible!)\n",
          adap->name);
-  return 0;
+  return -1;
 }
 
 /* Algorithm slave_recv call-back implementation. Can't do that... */
@@ -96,7 +96,7 @@ int isa_slave_recv (struct isa_adapter *adap, char *data, int len)
   printk("isa.o: isa_slave_recv called for adapter `%s' "
          "(no i2c level access possible!)\n",
          adap->name);
-  return 0;
+  return -1;
 }
 
 /* Here we can put additional calls to modify the workings of the algorithm.
diff --git a/kernel/smbus.c b/kernel/smbus.c
index ddd7ba3b..c0fa8a51 100644
--- a/kernel/smbus.c
+++ b/kernel/smbus.c
@@ -189,7 +189,7 @@ int smbus_master_xfer (struct smbus_adapter *adap, struct i2c_msg msgs[],
   printk("smbus.o: smbus_master_xfer called for adapter `%s' "
          "(no i2c level access possible!)\n",
          adap->name);
-  return 0;
+  return -1;
 }
 
 /* Algorithm slave_send call-back implementation. Can't do that... */
@@ -198,7 +198,7 @@ int smbus_slave_send (struct smbus_adapter *adap, char *data, int len)
   printk("smbus.o: smbus_slave_send called for adapter `%s' "
          "(no i2c level access possible!)\n",
          adap->name);
-  return 0;
+  return -1;
 }
 
 /* Algorithm slave_recv call-back implementation. Can't do that... */
@@ -207,7 +207,7 @@ int smbus_slave_recv (struct smbus_adapter *adap, char *data, int len)
   printk("smbus.o: smbus_slave_recv called for adapter `%s' "
          "(no i2c level access possible!)\n",
          adap->name);
-  return 0;
+  return -1;
 }
 
 /* Here we can put additional calls to modify the workings of the algorithm.
diff --git a/src/isa.c b/src/isa.c
index 061acb45..1a5daf91 100644
--- a/src/isa.c
+++ b/src/isa.c
@@ -78,7 +78,7 @@ int isa_master_xfer (struct isa_adapter *adap, struct i2c_msg msgs[],
   printk("isa.o: isa_master_xfer called for adapter `%s' "
          "(no i2c level access possible!)\n",
          adap->name);
-  return 0;
+  return -1;
 }
 
 /* Algorithm slave_send call-back implementation. Can't do that... */
@@ -87,7 +87,7 @@ int isa_slave_send (struct isa_adapter *adap, char *data, int len)
   printk("isa.o: isa_slave_send called for adapter `%s' "
          "(no i2c level access possible!)\n",
          adap->name);
-  return 0;
+  return -1;
 }
 
 /* Algorithm slave_recv call-back implementation. Can't do that... */
@@ -96,7 +96,7 @@ int isa_slave_recv (struct isa_adapter *adap, char *data, int len)
   printk("isa.o: isa_slave_recv called for adapter `%s' "
          "(no i2c level access possible!)\n",
          adap->name);
-  return 0;
+  return -1;
 }
 
 /* Here we can put additional calls to modify the workings of the algorithm.
diff --git a/src/smbus.c b/src/smbus.c
index ddd7ba3b..c0fa8a51 100644
--- a/src/smbus.c
+++ b/src/smbus.c
@@ -189,7 +189,7 @@ int smbus_master_xfer (struct smbus_adapter *adap, struct i2c_msg msgs[],
   printk("smbus.o: smbus_master_xfer called for adapter `%s' "
          "(no i2c level access possible!)\n",
          adap->name);
-  return 0;
+  return -1;
 }
 
 /* Algorithm slave_send call-back implementation. Can't do that... */
@@ -198,7 +198,7 @@ int smbus_slave_send (struct smbus_adapter *adap, char *data, int len)
   printk("smbus.o: smbus_slave_send called for adapter `%s' "
          "(no i2c level access possible!)\n",
          adap->name);
-  return 0;
+  return -1;
 }
 
 /* Algorithm slave_recv call-back implementation. Can't do that... */
@@ -207,7 +207,7 @@ int smbus_slave_recv (struct smbus_adapter *adap, char *data, int len)
   printk("smbus.o: smbus_slave_recv called for adapter `%s' "
          "(no i2c level access possible!)\n",
          adap->name);
-  return 0;
+  return -1;
 }
 
 /* Here we can put additional calls to modify the workings of the algorithm.