diff --git a/Tools/px_generate_params.py b/Tools/px_generate_params.py
index 0efe778683..3df124f523 100755
--- a/Tools/px_generate_params.py
+++ b/Tools/px_generate_params.py
@@ -3,8 +3,8 @@ import xml.etree.ElementTree as ET
 import os
 
 if len(os.sys.argv) != 2:
-	print "Error in %s" % os.sys.argv[0]
-	print "Usage: %s <parameters.xml>"
+	print("Error in %s" % os.sys.argv[0])
+	print("Usage: %s <parameters.xml>" % os.sys.argv[0])
 	raise SystemExit
 
 fp_header = open("px4_parameters.h", "w")
diff --git a/Tools/px_romfs_pruner.py b/Tools/px_romfs_pruner.py
index 78e4e69f72..85ff678b93 100644
--- a/Tools/px_romfs_pruner.py
+++ b/Tools/px_romfs_pruner.py
@@ -77,7 +77,7 @@ def main():
 
                         # overwrite old scratch file
                         with open(file_path, "wb") as f:
-                                f.write(pruned_content)
+                                f.write(pruned_content.encode("ascii", errors='strict'))
 
 
 if __name__ == '__main__':
diff --git a/cmake/nuttx/bin_to_obj.py b/cmake/nuttx/bin_to_obj.py
index a4ad3d94df..64ba864295 100755
--- a/cmake/nuttx/bin_to_obj.py
+++ b/cmake/nuttx/bin_to_obj.py
@@ -41,7 +41,7 @@ def run_cmd(cmd, d):
     #print(cmd)
     proc = subprocess.Popen(cmd.split(), stdout=PIPE, stderr=PIPE)
     stdout, stderr = proc.communicate()
-    if stderr != "":
+    if stderr.decode() != "":
         raise RuntimeError(stderr)
     return stdout
 
@@ -57,7 +57,7 @@ run_cmd("{ld:s} -r -o {obj:s}.bin.o {obj:s}.c.o -b binary {in_bin:s}",
 stdout = run_cmd("{nm:s} -p --radix=x {obj:s}.bin.o", locals())
 re_string = r"^([0-9A-F-a-f]+) .*{sym:s}_size\n".format(**locals())
 re_size = re.compile(re_string, re.MULTILINE)
-size_match = re.search(re_size, stdout)
+size_match = re.search(re_size, stdout.decode())
 try:
     size = size_match.group(1)
 except AttributeError as e: