--- a/scripts/mono-heapviz
+++ b/scripts/mono-heapviz
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/python3
 
 # Generate a heap visualization for SGen from the heap dump written by
 # mono if the MONO_GC_DEBUG is set to something like
diff -up mono-5.18.1.0/mono/mini/genmdesc.py.py3 mono-5.18.1.0/mono/mini/genmdesc.py
--- mono-5.18.1.0/mono/mini/genmdesc.py.py3	2019-03-28 06:56:35.765851125 -0400
+++ mono-5.18.1.0/mono/mini/genmdesc.py	2019-03-28 06:56:44.805851125 -0400
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/python3
 
 #
 # This tool is used to generate the cpu-<ARCH>.h files used by the JIT. The input is the
diff -up mono-5.18.1.0/mono/mini/Makefile.am.in.py3 mono-5.18.1.0/mono/mini/Makefile.am.in
--- mono-5.18.1.0/mono/mini/Makefile.am.in.py3	2019-03-28 07:01:10.975851125 -0400
+++ mono-5.18.1.0/mono/mini/Makefile.am.in	2019-03-28 07:01:35.395851125 -0400
@@ -780,7 +780,7 @@ MemoryIntrinsics.dll: MemoryIntrinsics.i
 
 GENMDESC_OPTS=
 
-GENMDESC_PRG=python $(srcdir)/genmdesc.py $(target_define) $(srcdir)
+GENMDESC_PRG=python3 $(srcdir)/genmdesc.py $(target_define) $(srcdir)
 
 cpu-wasm.h: mini-ops.h cpu-wasm.md $(srcdir)/genmdesc.py
 	$(GENMDESC_PRG) cpu-wasm.h wasm_desc $(srcdir)/cpu-wasm.md
diff -up mono-5.18.1.0/mono/mini/Makefile.am.py3 mono-5.18.1.0/mono/mini/Makefile.am
--- mono-5.18.1.0/mono/mini/Makefile.am.py3	2019-03-28 07:06:02.235851125 -0400
+++ mono-5.18.1.0/mono/mini/Makefile.am	2019-03-28 07:06:06.385851125 -0400
@@ -780,7 +780,7 @@ MemoryIntrinsics.dll: MemoryIntrinsics.i
 
 GENMDESC_OPTS=
 
-GENMDESC_PRG=python $(srcdir)/genmdesc.py $(target_define) $(srcdir)
+GENMDESC_PRG=python3 $(srcdir)/genmdesc.py $(target_define) $(srcdir)
 
 cpu-wasm.h: mini-ops.h cpu-wasm.md $(srcdir)/genmdesc.py
 	$(GENMDESC_PRG) cpu-wasm.h wasm_desc $(srcdir)/cpu-wasm.md
diff -up mono-5.18.1.0/mono/mini/Makefile.in.py3 mono-5.18.1.0/mono/mini/Makefile.in
--- mono-5.18.1.0/mono/mini/Makefile.in.py3	2019-03-28 07:06:12.805851125 -0400
+++ mono-5.18.1.0/mono/mini/Makefile.in	2019-03-28 07:06:21.575851125 -0400
@@ -1287,7 +1287,7 @@ libmonoincludedir = $(includedir)/mono-$
 libmonoinclude_HEADERS = jit.h
 CSFLAGS = -unsafe -nowarn:0219,0169,0414,0649,0618
 GENMDESC_OPTS = 
-GENMDESC_PRG = python $(srcdir)/genmdesc.py $(target_define) $(srcdir)
+GENMDESC_PRG = python3 $(srcdir)/genmdesc.py $(target_define) $(srcdir)
 LLVM_AOT_RUNTIME_OPTS = $(if $(LLVM),--llvm,)
 @AMD64_FALSE@LLVM_AOT_COMPILER_OPTS = 
 @AMD64_TRUE@LLVM_AOT_COMPILER_OPTS = $(if $(LLVM),llvmllc=-mattr=+sse3,)