diff --git a/build.gradle b/build.gradle
index 6e5465623..3c17d6f20 100644
--- a/build.gradle
+++ b/build.gradle
@@ -209,19 +209,22 @@ rootProject.ext {
 
 task runPresubmits(type: Exec) {
 
-  // Find a python version greater than 3.7.3 (this is somewhat arbitrary, we
-  // know we'd like at least 3.6, but 3.7.3 is the latest that ships with
-  // Debian so it seems like that should be available anywhere).
-  def MIN_PY_VER = 0x3070300
-  if (pyver('python') >= MIN_PY_VER) {
-    executable 'python'
-  } else if (pyver('/usr/bin/python3') >= MIN_PY_VER) {
-    executable '/usr/bin/python3'
-  } else {
-    throw new GradleException("No usable Python version found (build " +
-                              "requires at least python 3.7.3)");
-  }
   args('config/presubmits.py')
+
+  doFirst {
+    // Find a python version greater than 3.7.3 (this is somewhat arbitrary, we
+    // know we'd like at least 3.6, but 3.7.3 is the latest that ships with
+    // Debian so it seems like that should be available anywhere).
+    def MIN_PY_VER = 0x3070300
+    if (pyver('python') >= MIN_PY_VER) {
+      executable 'python'
+    } else if (pyver('/usr/bin/python3') >= MIN_PY_VER) {
+      executable '/usr/bin/python3'
+    } else {
+      throw new GradleException("No usable Python version found (build " +
+                                "requires at least python 3.7.3)");
+    }
+  }
 }
 
 def javadocSource = []