diff --git a/src/suprocess.cpp b/src/suprocess.cpp
--- a/src/suprocess.cpp
+++ b/src/suprocess.cpp
@@ -25,14 +25,6 @@
 #include <ksharedconfig.h>
 #include <kuser.h>
 
-#ifndef __PATH_SU
-#define __PATH_SU "false"
-#endif
-
-#ifndef __PATH_SUDO
-#define __PATH_SUDO "false"
-#endif
-
 #ifdef KDESU_USE_SUDO_DEFAULT
 #  define DEFAULT_SUPER_USER_COMMAND QStringLiteral("sudo")
 #else
@@ -128,11 +120,16 @@
     args += "-"; // krazy:exclude=doublequote_chars (QList, not QString)
 
     QByteArray command;
+#ifdef __PATH_SUDO
     if (d->superUserCommand == QLatin1String("sudo")) {
         command = __PATH_SUDO;
-    } else {
+    }
+#endif
+#ifdef __PATH_SU
+    if (d->superUserCommand == QLatin1String("su")) {
         command = __PATH_SU;
     }
+#endif
 
     if (QT_ACCESS(command.constData(), X_OK) != 0) {
         command = QFile::encodeName(QStandardPaths::findExecutable(d->superUserCommand));