Index: b/configure.ac
===================================================================
--- b/configure.ac
+++ b/configure.ac
@@ -505,15 +505,15 @@
 dnl Checks for Qt4 libraries.  Deal correctly with $pinentry_qt4 = maybe.
 dnl
 if test "$pinentry_qt4" != "no"; then
-PKG_CHECK_MODULES(QT4_CORE, QtCore,,
-if test "$pinentry_qt4" = "yes"; then
-    AC_MSG_ERROR([[
-***
-*** Qt4 Core is required.
-***]])
-else
-    pinentry_qt4=no
-fi)
+	PKG_CHECK_MODULES(
+		QT4_CORE,
+		QtCore,
+		,
+		[
+			AC_MSG_WARN([pkg-config could not find the module QtCore])
+			pinentry_qt4=no
+		]
+	)
 fi
 
 if test "$pinentry_qt4" != "no"; then