diff --git a/src/test/CMakeLists.txt b/src/test/CMakeLists.txt
--- a/src/test/CMakeLists.txt
+++ b/src/test/CMakeLists.txt
@@ -3,33 +3,23 @@
 project(bitcoin-test)
 
 # Process json files.
-find_program(HEXDUMP "hexdump")
-find_program(SED "sed")
+find_program(PYTHON python)
 function(gen_json_header NAME)
 	set(HEADERS "")
 	foreach(f ${ARGN})
-		set(hex "${CMAKE_CURRENT_BINARY_DIR}/${f}.hex")
 		set(h "${CMAKE_CURRENT_BINARY_DIR}/${f}.h")
-		add_custom_command(OUTPUT ${hex}
-			COMMAND ${HEXDUMP}
-			ARGS
-				-v
-				-e "8/1 \"0x%02x, \""
-				-e "\"\\n\""
-				"${CMAKE_CURRENT_SOURCE_DIR}/${f}" > ${hex}
-			MAIN_DEPENDENCY ${f}
-			VERBATIM
-		)
+
 		# Get the proper name for the test variable.
 		get_filename_component(TEST_NAME ${f} NAME_WE)
 		add_custom_command(OUTPUT ${h}
-			COMMAND ${SED}
+			COMMAND ${PYTHON}
 			ARGS
-				-e "s/0x  ,//g"
-				-e "1 s/^/namespace json_tests{\\nstatic unsigned const char ${TEST_NAME}[] = {\\n/"
-				-e "\${s:\$:\\n\\};\\n\\}; // namespace json_tests:}"
-				< ${hex} > ${h}
-			MAIN_DEPENDENCY ${hex}
+				"${CMAKE_CURRENT_SOURCE_DIR}/data/generate_header.py"
+				"${TEST_NAME}"
+				"${CMAKE_CURRENT_SOURCE_DIR}/${f}" > ${h}
+			MAIN_DEPENDENCY ${f}
+			DEPENDS
+				"data/generate_header.py"
 			VERBATIM
 		)
 		list(APPEND HEADERS ${h})
diff --git a/src/test/data/generate_header.py b/src/test/data/generate_header.py
new file mode 100755
--- /dev/null
+++ b/src/test/data/generate_header.py
@@ -0,0 +1,24 @@
+#!/usr/bin/env python
+# Copyright (c) 2018 The Bitcoin developers
+
+import os
+import sys
+
+
+def main(test_name, input_file):
+    with open(input_file, "rb") as f:
+        contents = f.read()
+
+    print("namespace json_tests{")
+    print("   static unsigned const char {}[] = {{".format(test_name))
+    print(", ".join(map(lambda x: "0x{:02x}".format(ord(x)), contents)))
+    print(" };")
+    print("};")
+
+
+if __name__ == "__main__":
+    if len(sys.argv) != 3:
+        print("We need additional pylons!")
+        os.exit(1)
+
+    main(sys.argv[1], sys.argv[2])