diff --git a/src/libmain/shared.cc b/src/libmain/shared.cc
index a5401ba5d..68016b0d7 100644
--- a/src/libmain/shared.cc
+++ b/src/libmain/shared.cc
@@ -207,6 +207,9 @@ static void initAndRun(int argc, char * * argv)
 }
 
 
+bool setuidMode = false;
+
+
 static void setuidInit()
 {
     /* Don't do anything if this is not a setuid binary. */
diff --git a/src/libmain/shared.hh b/src/libmain/shared.hh
index 20262004b..2c574d148 100644
--- a/src/libmain/shared.hh
+++ b/src/libmain/shared.hh
@@ -25,7 +25,7 @@ Path makeRootName(const Path & gcRoot, int & counter);
 void printGCWarning();
 
 /* Whether we're running setuid. */
-bool setuidMode = false;
+extern bool setuidMode;
 
 }