diff --git a/libIDL-0.8.14-long-long-format-warnings.patch b/libIDL-0.8.14-long-long-format-warnings.patch
new file mode 100644
index 0000000..b167400
--- /dev/null
+++ b/libIDL-0.8.14-long-long-format-warnings.patch
@@ -0,0 +1,19 @@
+On platforms (such as 64-bit Linux), where long long int and long int are both
+64-bit, we can have IDL_LL defined to ll (format with %%lld) while
+IDL_longlong_t, which is just gint64, may be ultimately defined to long int.
+This results in compiler warnings about the mismatch between the long long
+format and long parameter, even though the types are compatible. We can fix
+this with a cast to long long before formatting.
+
+diff -Naur libIDL-0.8.14-original/parser.y libIDL-0.8.14/parser.y
+--- libIDL-0.8.14-original/parser.y	2009-04-18 08:20:37.000000000 -0400
++++ libIDL-0.8.14/parser.y	2021-02-03 12:37:11.067509562 -0500
+@@ -1354,7 +1354,7 @@
+ 	} else if (value < 0) {
+ 		yywarningv (IDL_WARNING1, "Cannot use negative value %"
+ 			    IDL_LL "d, using %" IDL_LL "d",
+-			   value, -value);
++			   (long long) value, (long long) -value);
+ 		if (ident)
+ 			IDL_tree_warning (ident,
+ 					  IDL_WARNING1, "From constant declared here");
diff --git a/libIDL.spec b/libIDL.spec
index 446667e..50cf260 100644
--- a/libIDL.spec
+++ b/libIDL.spec
@@ -16,6 +16,13 @@ License:        LGPLv2+
 # Fix paths reported by the libIDL-config-2 tool to conform with Fedora
 # multilib installation paths:
 Patch0:         %{name}-0.8.6-multilib.patch
+# On platforms (such as 64-bit Linux), where long long int and long int are
+# both 64-bit, we can have IDL_LL defined to ll (format with %%lld) while
+# IDL_longlong_t, which is just gint64, may be ultimately defined to long int.
+# This results in compiler warnings about the mismatch between the long long
+# format and long parameter, even though the types are compatible. We can fix
+# this with a cast to (long long) before formatting.
+Patch1:         %{name}-0.8.14-long-long-format-warnings.patch
 
 BuildRequires:  gcc
 BuildRequires:  make
@@ -91,6 +98,7 @@ rm '%{buildroot}%{_libdir}/%{name}-2.la'
 - Drop obsolete %%ldconfig_scriptlets macro
 - Use much stricter path globs
 - Use %%name macro
+- Patch long long format warnings
 
 * Tue Jan 26 2021 Fedora Release Engineering <releng@fedoraproject.org> - 0.8.14-23
 - Rebuilt for https://fedoraproject.org/wiki/Fedora_34_Mass_Rebuild