diff --git a/lib/default.nix b/lib/default.nix
index 50320669e28..ccae0bbc3ab 100644
--- a/lib/default.nix
+++ b/lib/default.nix
@@ -66,8 +66,9 @@ let
       stringLength sub substring tail trace;
     inherit (self.trivial) id const pipe concat or and bitAnd bitOr bitXor
       bitNot boolToString mergeAttrs flip mapNullable inNixShell isFloat min max
-      importJSON importTOML warn info showWarnings nixpkgsVersion version mod compare
-      splitByAndCompare functionArgs setFunctionArgs isFunction toHexString toBaseDigits;
+      importJSON importTOML warn warnIf info showWarnings nixpkgsVersion version
+      mod compare splitByAndCompare functionArgs setFunctionArgs isFunction
+      toHexString toBaseDigits;
     inherit (self.fixedPoints) fix fix' converge extends composeExtensions
       composeManyExtensions makeExtensible makeExtensibleWithCustomName;
     inherit (self.attrsets) attrByPath hasAttrByPath setAttrByPath
diff --git a/lib/trivial.nix b/lib/trivial.nix
index be6d0115f5b..f6f5da5998f 100644
--- a/lib/trivial.nix
+++ b/lib/trivial.nix
@@ -297,12 +297,15 @@ rec {
   # Usage:
   # {
   #   foo = lib.warn "foo is deprecated" oldFoo;
+  #   bar = lib.warnIf (bar == "") "Empty bar is deprecated" bar;
   # }
   #
   # TODO: figure out a clever way to integrate location information from
   # something like __unsafeGetAttrPos.
 
   warn = msg: builtins.trace "warning: ${msg}";
+  warnIf = cond: msg: if cond then warn msg else id;
+
   info = msg: builtins.trace "INFO: ${msg}";
 
   showWarnings = warnings: res: lib.fold (w: x: warn w x) res warnings;