diff --git a/perl-Crypt-CBC.spec b/perl-Crypt-CBC.spec
index caffc3c..f4160f4 100644
--- a/perl-Crypt-CBC.spec
+++ b/perl-Crypt-CBC.spec
@@ -1,7 +1,7 @@
 Summary:        Encrypt Data with Cipher Block Chaining Mode
 Name:           perl-Crypt-CBC
 Version:        3.02
-Release:        1%{?dist}
+Release:        2%{?dist}
 # Upstream confirms that they're under the same license as perl.
 # Wording in CBC.pm is less than clear, but still.
 License:        GPL+ or Artistic
@@ -24,7 +24,8 @@ BuildRequires:  perl(Crypt::PBKDF2)
 BuildRequires:  perl(Digest::MD5) >= 2.00
 BuildRequires:  perl(Digest::SHA)
 BuildRequires:  perl(File::Basename)
-BuildRequires:  perl(Math::Int128)
+# Not available on 32-bit platforms (#1948957)
+#BuildRequires:  perl(Math::Int128)
 BuildRequires:  perl(Scalar::Util)
 BuildRequires:  perl(strict)
 BuildRequires:  perl(vars)
@@ -47,8 +48,9 @@ BuildRequires:  perl(Crypt::Rijndael)
 BuildRequires:  perl(Crypt::IDEA)
 # Dependencies
 Requires:       perl(:MODULE_COMPAT_%(eval "`perl -V:version`"; echo $version))
-Requires:       perl(Math::Int128)
 Requires:       perl(Scalar::Util)
+# Optional module needed for CTR mode
+Recommends:     perl(Math::Int128)
 
 %description
 This is Crypt::CBC, a Perl-only implementation of the cryptographic
@@ -79,6 +81,10 @@ make test
 %{_mandir}/man3/Crypt::CBC.3*
 
 %changelog
+* Thu Apr 15 2021 Paul Howarth <paul@city-fan.org> - 3.02-2
+- Soften dependency on perl(Math::Int128) (needed for CTR mode) as it's not
+  available on 32-bit platforms (#1948957)
+
 * Mon Apr 12 2021 Paul Howarth <paul@city-fan.org> - 3.02-1
 - Update to 3.02
   - CTR mode now requires the Math::Int128 module, which gives a ~5x