diff --git a/tools/qmake/mkspecs/features/functions.prf b/tools/qmake/mkspecs/features/functions.prf
index 0d15d0761c9b7509987392da9c16417a383cd805..d84ef9d6f082095b02c62873d3c558e5103e4eef 100644
--- a/tools/qmake/mkspecs/features/functions.prf
+++ b/tools/qmake/mkspecs/features/functions.prf
@@ -10,8 +10,8 @@ defineTest(isPlatformSupported) {
 }
 
 defineTest(isPythonVersionSupported) {
-  python_major_version = $$system("python -c 'import sys; print sys.version_info.major'")
-  python_minor_version = $$system("python -c 'import sys; print sys.version_info.minor'")
+  python_major_version = $$system('python -c "import sys; print sys.version_info.major"')
+  python_minor_version = $$system('python -c "import sys; print sys.version_info.minor"')
   greaterThan(python_major_version, 1): greaterThan(python_minor_version, 6): return(true)
   return(false)
 }