diff --git a/cpp-lib/cpp/cpp.pro b/cpp-lib/cpp/cpp.pro
index 51769d5..dd88be9 100644
--- a/cpp-lib/cpp/cpp.pro
+++ b/cpp-lib/cpp/cpp.pro
@@ -1,6 +1,6 @@
 QT          += widgets
 TEMPLATE    = lib
-CONFIG      += plugin release no_keywords
+CONFIG      += c++17 plugin release no_keywords
 INCLUDEPATH = /usr/local/include
 LIBS        = -L/usr/local/lib -lecl
 DESTDIR     = ../
diff --git a/examples/advanced-qml-auto-reload/app.pro b/examples/advanced-qml-auto-reload/app.pro
index 2f2683a..57f1e6b 100644
--- a/examples/advanced-qml-auto-reload/app.pro
+++ b/examples/advanced-qml-auto-reload/app.pro
@@ -24,7 +24,7 @@ win32:  PRE_TARGETDEPS = tmp/app.lib
 
 QT          += quick qml
 TEMPLATE    = app
-CONFIG      += no_keywords release
+CONFIG      += c++17 no_keywords release
 DEFINES     += DESKTOP_APP INI_LISP INI_ECL_CONTRIB
 INCLUDEPATH = /usr/local/include
 ECL_VERSION = $$lower($$system(ecl -v))
@@ -88,6 +88,3 @@ system(ecl -shell qml/.create-qml-loaders.lisp)
 
 RESOURCES += $$files(qml/*)
 RESOURCES += $$files(qml/.ext/*)
-
-QMAKE_CXXFLAGS += -std=c++17
-
diff --git a/examples/app-template/app.pro b/examples/app-template/app.pro
index ac7532f..e39c8cd 100644
--- a/examples/app-template/app.pro
+++ b/examples/app-template/app.pro
@@ -24,7 +24,7 @@ win32:  PRE_TARGETDEPS = tmp/app.lib
 
 QT          += quick qml
 TEMPLATE    = app
-CONFIG      += no_keywords release
+CONFIG      += c++17 no_keywords release
 DEFINES     = DESKTOP_APP INI_LISP
 INCLUDEPATH = /usr/local/include
 LIBS        = -L/usr/local/lib -lecl
@@ -66,5 +66,3 @@ HEADERS += ../../src/cpp/main.h
 SOURCES += ../../src/cpp/main.cpp
 
 RESOURCES = $$files(qml/*)
-
-QMAKE_CXXFLAGS += -std=c++17
diff --git a/examples/cl-repl/app.pro b/examples/cl-repl/app.pro
index 9193306..b98d238 100644
--- a/examples/cl-repl/app.pro
+++ b/examples/cl-repl/app.pro
@@ -24,7 +24,7 @@ win32:  PRE_TARGETDEPS = tmp/app.lib
 
 QT          += quick qml
 TEMPLATE    = app
-CONFIG      += no_keywords release
+CONFIG      += c++17 no_keywords release
 DEFINES     += DESKTOP_APP INI_LISP INI_ECL_CONTRIB QT_EXTENSION
 INCLUDEPATH = /usr/local/include ../../../src/cpp
 ECL_VERSION = $$lower($$system(ecl -v))
@@ -87,6 +87,3 @@ HEADERS += ../../src/cpp/main.h   cpp/qt.h
 SOURCES += ../../src/cpp/main.cpp cpp/qt.cpp
 
 RESOURCES = $$files(qml/*)
-
-QMAKE_CXXFLAGS += -std=c++17
-
diff --git a/examples/cl-repl/cpp/qt.pro b/examples/cl-repl/cpp/qt.pro
index 5c4c602..915a6ab 100644
--- a/examples/cl-repl/cpp/qt.pro
+++ b/examples/cl-repl/cpp/qt.pro
@@ -1,6 +1,6 @@
 QT          += gui quick
 TEMPLATE    = lib
-CONFIG      += plugin release no_keywords
+CONFIG      += c++17 plugin release no_keywords
 DEFINES     += PLUGIN
 INCLUDEPATH = /usr/local/include ../../../src/cpp
 LIBS        = -L/usr/local/lib -lecl
@@ -25,5 +25,3 @@ win32 {
 
   LIBS += -L../../../platforms/windows/lib
 }
-
-QMAKE_CXXFLAGS += -std=c++17
diff --git a/examples/clog-demo/app.pro b/examples/clog-demo/app.pro
index b31f2f9..23e661e 100644
--- a/examples/clog-demo/app.pro
+++ b/examples/clog-demo/app.pro
@@ -24,7 +24,7 @@ win32:  PRE_TARGETDEPS = tmp/app.lib
 
 QT          += quick qml websockets webview
 TEMPLATE    = app
-CONFIG      += no_keywords release
+CONFIG      += c++17 no_keywords release
 DEFINES     += DESKTOP_APP INI_LISP INI_ECL_CONTRIB INI_ASDF INI_WEBVIEW
 INCLUDEPATH = /usr/local/include
 ECL_VERSION = $$lower($$system(ecl -v))
@@ -83,6 +83,3 @@ HEADERS += ../../src/cpp/main.h
 SOURCES += ../../src/cpp/main.cpp
 
 RESOURCES += $$files(qml/*)
-
-QMAKE_CXXFLAGS += -std=c++17
-
diff --git a/examples/swank-server/app.pro b/examples/swank-server/app.pro
index 3a83f96..77afbf3 100644
--- a/examples/swank-server/app.pro
+++ b/examples/swank-server/app.pro
@@ -24,7 +24,7 @@ win32:  PRE_TARGETDEPS = tmp/app.lib
 
 QT          += quick qml
 TEMPLATE    = app
-CONFIG      += no_keywords release
+CONFIG      += c++17 no_keywords release
 DEFINES     += DESKTOP_APP INI_LISP INI_ECL_CONTRIB
 INCLUDEPATH = /usr/local/include
 ECL_VERSION = $$lower($$system(ecl -v))
@@ -85,6 +85,3 @@ HEADERS += ../../src/cpp/main.h
 SOURCES += ../../src/cpp/main.cpp
 
 RESOURCES = $$files(qml/*)
-
-QMAKE_CXXFLAGS += -std=c++17
-
diff --git a/examples/tilt-sensor/app.pro b/examples/tilt-sensor/app.pro
index bb2b39e..483b027 100644
--- a/examples/tilt-sensor/app.pro
+++ b/examples/tilt-sensor/app.pro
@@ -24,7 +24,7 @@ win32:  PRE_TARGETDEPS = tmp/app.lib
 
 QT          += quick qml
 TEMPLATE    = app
-CONFIG      += no_keywords release
+CONFIG      += c++17 no_keywords release
 DEFINES     = DESKTOP_APP INI_LISP
 INCLUDEPATH = /usr/local/include
 LIBS        = -L/usr/local/lib -lecl
@@ -69,5 +69,3 @@ HEADERS += ../../src/cpp/main.h
 SOURCES += ../../src/cpp/main.cpp
 
 RESOURCES = $$files(qml/*)
-
-QMAKE_CXXFLAGS += -std=c++17
diff --git a/src/lqml-lib.pro b/src/lqml-lib.pro
index 0e78f67..8bf75d2 100644
--- a/src/lqml-lib.pro
+++ b/src/lqml-lib.pro
@@ -1,6 +1,6 @@
 QT          += quick qml
 TEMPLATE    = lib
-CONFIG      += staticlib no_keywords release
+CONFIG      += c++17 staticlib no_keywords release
 LIBS        = -L/usr/local/lib -lecl
 TARGET      = lqml
 OBJECTS_DIR = ./tmp
@@ -52,8 +52,6 @@ SOURCES += \
   cpp/qt_ecl.cpp \
   cpp/single_shot.cpp
 
-QMAKE_CXXFLAGS += -std=c++17
-
 # compile Lisp code
 
 android {
diff --git a/src/lqml.pro b/src/lqml.pro
index 127fd80..cb33737 100644
--- a/src/lqml.pro
+++ b/src/lqml.pro
@@ -1,6 +1,6 @@
 QT          += quick qml
 TEMPLATE    = app
-CONFIG      += no_keywords release
+CONFIG      += c++17 no_keywords release
 INCLUDEPATH = /usr/local/include
 LIBS        = -L/usr/local/lib -lecl -llisp
 TARGET      = lqml
@@ -53,7 +53,5 @@ SOURCES += \
   cpp/single_shot.cpp \
   cpp/main.cpp
 
-QMAKE_CXXFLAGS += -std=c++17
-
 QMAKE_PRE_LINK = ecl -shell $$PWD/make.lisp