diff --git a/CHANGES b/CHANGES
index 79d1c799..249dd128 100644
--- a/CHANGES
+++ b/CHANGES
@@ -22,6 +22,7 @@ SVN HEAD
   Program sensors-detect: Add SMSC DME1737 detection
                           Add EPoX EP1308 detection (Hans Edgington)
                           Add Intel Core thermal sensor detection
+                          Preallocate memory for I2C_FUNCS ioctl (#2138)
 
 2.10.1 (20060924)
   File doc/developers/checklist renamed to dev/developers/release_checklist
diff --git a/prog/detect/sensors-detect b/prog/detect/sensors-detect
index a8911375..f11b3b01 100755
--- a/prog/detect/sensors-detect
+++ b/prog/detect/sensors-detect
@@ -2392,9 +2392,9 @@ use constant I2C_FUNC_SMBUS_READ_BYTE	=> 0x00020000;
 sub i2c_get_funcs($)
 {
   my $file = shift;
-  my $funcs;
+  my $funcs = pack "L", 0; # Allocate space
 
-  ioctl $file, IOCTL_I2C_FUNCS, $funcs='' or return -1;
+  ioctl $file, IOCTL_I2C_FUNCS, $funcs or return -1;
   $funcs = unpack "L", $funcs;
 
   return $funcs;