diff --git a/INSTALL b/INSTALL
index 3270743b7..5e152b71f 100644
--- a/INSTALL
+++ b/INSTALL
@@ -42,7 +42,7 @@ To build GRUB's graphical terminal (gfxterm), you need:
 If you use a development snapshot or want to hack on GRUB you may
 need the following.
 
-* Python 2.6 or later
+* Python 3 (NOTE: python 2.6 should still work, but it's not tested)
 * Autoconf 2.63 or later
 * Automake 1.11 or later
 
@@ -87,9 +87,8 @@ The simplest way to compile this package is:
   
   3. Type `./bootstrap'.
 
-     * autogen.sh (called by bootstrap) uses python. By default the
-       invocation is "python", but it can be overridden by setting the
-       variable $PYTHON.
+     The autogen.sh (called by bootstrap) uses python. By default autodetect
+     it, but it can be overridden by setting the PYTHON variable.
 
   4. Type `./configure' to configure the package for your system.
      If you're using `csh' on an old version of System V, you might
diff --git a/autogen.sh b/autogen.sh
index 31b0ced7e..5a5c356fd 100755
--- a/autogen.sh
+++ b/autogen.sh
@@ -7,8 +7,21 @@ if [ ! -e grub-core/lib/gnulib/stdlib.in.h ]; then
   exit 1
 fi
 
-# Set ${PYTHON} to plain 'python' if not set already
-: ${PYTHON:=python}
+# Detect python
+if [ -z "$PYTHON" ]; then
+  for i in python3 python; do
+    if command -v "$i" > /dev/null 2>&1; then
+      PYTHON="$i"
+      echo "Using $PYTHON..."
+      break
+    fi
+  done
+
+  if [ -z "$PYTHON" ]; then
+    echo "python not found." >&2
+    exit 1
+  fi
+fi
 
 export LC_COLLATE=C
 unset LC_ALL