diff --git a/pdf-create-empty b/pdf-create-empty
index a81401e..4347853 100755
--- a/pdf-create-empty
+++ b/pdf-create-empty
@@ -44,6 +44,10 @@ def die(reason):
     print(reason, file=sys.stderr)
     sys.exit(2)
 
+pyver = sys.version_info
+if not (pyver.major == 3 and pyver.minor >= 7):
+    die("Requires python 3.7 or later")
+
 parser = argparse.ArgumentParser(description='Create an empty, transparent PDF file.')
 parser.add_argument('-o', '--output', metavar='FILE', type=str, help='Output PDF file. (default: empty-DIMENSIONS.pdf)')
 parser.add_argument('-d', '--dimensions', type=str, default='3inx2in', help='The page dimensions of the file to create. Supports units pts, in, cm, and mm. (default: 3inx2in)')
diff --git a/pdf-from-text b/pdf-from-text
index dfb89cb..0d46b1f 100755
--- a/pdf-from-text
+++ b/pdf-from-text
@@ -94,5 +94,9 @@ def die(reason):
     print(reason, file=sys.stderr)
     sys.exit(2)
 
+pyver = sys.version_info
+if not (pyver.major == 3 and pyver.minor >= 7):
+    die("Requires python 3.7 or later")
+
 if __name__ == "__main__":
     main()
diff --git a/pdf-sign b/pdf-sign
index 8fb07a9..868836a 100755
--- a/pdf-sign
+++ b/pdf-sign
@@ -8,6 +8,14 @@
 
 import argparse, os, queue, re, subprocess, sys, tempfile, traceback, time
 
+def die(reason):
+    print(reason, file=sys.stderr)
+    sys.exit(1)
+
+pyver = sys.version_info
+if not (pyver.major == 3 and pyver.minor >= 7):
+    die("Requires python 3.7 or later")
+
 # Inspired by https://unix.stackexchange.com/a/141496
 def main(args):
     if not hasQpdf and not has("pdftk"):
@@ -696,10 +704,6 @@ def fromCmdOutput(cmd, pattern):
     result=sp.stdout.decode('utf-8')
     return m(pattern, result)
 
-def die(reason):
-    print(reason, file=sys.stderr)
-    sys.exit(1)
-
 # Monkey-patch argparse if necessary
 if not 'BooleanOptionalAction' in dir(argparse):
     class BooleanOptionalAction(argparse.Action):