--- a/src/cxx_supportlib/Constants.h
+++ b/src/cxx_supportlib/Constants.h
@@ -58,7 +58,7 @@
 #define DEFAULT_MBUF_CHUNK_SIZE 4096
 #define DEFAULT_NODEJS "nodejs"
 #define DEFAULT_POOL_IDLE_TIME 300
-#define DEFAULT_PYTHON "python"
+#define DEFAULT_PYTHON "python3"
 #define DEFAULT_RESPONSE_BUFFER_HIGH_WATERMARK 134217728
 #define DEFAULT_RUBY "ruby"
 #define DEFAULT_SOCKET_BACKLOG 2048
--- a/src/ruby_supportlib/phusion_passenger/constants.rb
+++ b/src/ruby_supportlib/phusion_passenger/constants.rb
@@ -46,7 +46,7 @@ module PhusionPassenger
     DEFAULT_INTEGRATION_MODE = "standalone"
     DEFAULT_SOCKET_BACKLOG = 2048
     DEFAULT_RUBY = "ruby"
-    DEFAULT_PYTHON = "python"
+    DEFAULT_PYTHON = "python3"
     DEFAULT_NODEJS = "nodejs"
     DEFAULT_MAX_POOL_SIZE = 6
     DEFAULT_POOL_IDLE_TIME = 300