diff --git a/qtdeclarative.pro b/qtdeclarative.pro
index 5b94da9b6..0e3496ce8 100644
--- a/qtdeclarative.pro
+++ b/qtdeclarative.pro
@@ -2,7 +2,7 @@ CONFIG += tests_need_tools examples_need_tools
 load(qt_parts)
 
 !python_available {
-    py_out = $$system('python -c "print(1)"')
+    py_out = $$system('python3 -c "print(1)"')
     !equals(py_out, 1): error("Building QtQml requires Python.")
     tmp = python_available
     CONFIG += $$tmp
diff --git a/src/3rdparty/masm/masm.pri b/src/3rdparty/masm/masm.pri
index 0e63ac2ce..7a30ab64e 100644
--- a/src/3rdparty/masm/masm.pri
+++ b/src/3rdparty/masm/masm.pri
@@ -58,7 +58,7 @@ contains(DEFINES, WTF_USE_UDIS86=1) {
     udis86.output = udis86_itab.h
     udis86.input = ITAB
     udis86.CONFIG += no_link
-    udis86.commands = python $$PWD/disassembler/udis86/itab.py ${QMAKE_FILE_IN}
+    udis86.commands = python3 $$PWD/disassembler/udis86/itab.py ${QMAKE_FILE_IN}
     QMAKE_EXTRA_COMPILERS += udis86
 
     udis86_tab_cfile.target = $$OUT_PWD/udis86_itab.c
@@ -113,7 +113,7 @@ retgen.output = $$GENERATEDDIR/RegExpJitTables.h
 retgen.script = $$PWD/yarr/create_regex_tables
 retgen.input = retgen.script
 retgen.CONFIG += no_link
-retgen.commands = python $$retgen.script > ${QMAKE_FILE_OUT}
+retgen.commands = python3 $$retgen.script > ${QMAKE_FILE_OUT}
 QMAKE_EXTRA_COMPILERS += retgen
 
 # Taken from WebKit/Tools/qmake/mkspecs/features/unix/default_post.prf
diff --git a/src/3rdparty/masm/yarr/create_regex_tables b/src/3rdparty/masm/yarr/create_regex_tables
index 4c3dbbe3f..d13084d6c 100644
--- a/src/3rdparty/masm/yarr/create_regex_tables
+++ b/src/3rdparty/masm/yarr/create_regex_tables
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 
 # Copyright (C) 2010, 2013-2017 Apple Inc. All rights reserved.
 # 
diff --git a/src/3rdparty/masm/yarr/generateYarrCanonicalizeUnicode b/src/3rdparty/masm/yarr/generateYarrCanonicalizeUnicode
index a103bcdf1..20a358c1a 100644
--- a/src/3rdparty/masm/yarr/generateYarrCanonicalizeUnicode
+++ b/src/3rdparty/masm/yarr/generateYarrCanonicalizeUnicode
@@ -1,4 +1,4 @@
-#! /usr/bin/env python
+#! /usr/bin/env python3
 
 # Copyright (C) 2016 Apple Inc. All rights reserved.
 #