diff --git a/source/configure b/source/configure
index abcdef1..1234567 100755
--- a/source/configure
+++ b/source/configure
@@ -9534,7 +9534,7 @@ else
     then
         echo "Spawning Python to generate data/rules.mk..."
         PYTHONPATH="$srcdir/python" \
-            $PYTHON -m icutools.databuilder \
+            "$PYTHON" -m icutools.databuilder \
             --mode gnumake \
             --seqmode parallel \
             --src_dir "$srcdir/data" \
@@ -9550,7 +9550,7 @@ else
     fi
     echo "Spawning Python to generate test/testdata/rules.mk..."
     PYTHONPATH="$srcdir/python" \
-        $PYTHON -m icutools.databuilder \
+        "$PYTHON" -m icutools.databuilder \
         --mode gnumake \
         --seqmode parallel \
         --src_dir "$srcdir/test/testdata" \