diff --git a/lib/trivial.nix b/lib/trivial.nix
index 0bcefcbc28de..fac0718a9e73 100644
--- a/lib/trivial.nix
+++ b/lib/trivial.nix
@@ -102,7 +102,7 @@ rec {
   # Pull in some builtins not included elsewhere.
   inherit (builtins)
     pathExists readFile isBool
-    isInt add sub lessThan
+    isInt isFloat add sub lessThan
     seq deepSeq genericClosure;
 
   inherit (lib.strings) fileContents;
diff --git a/lib/types.nix b/lib/types.nix
index 5aa09d33e9b3..cf6f2aa46e40 100644
--- a/lib/types.nix
+++ b/lib/types.nix
@@ -167,6 +167,13 @@ rec {
         # s32 = sign 32 4294967296;
       };
 
+    float = mkOptionType rec {
+        name = "float";
+        description = "floating point number";
+        check = isFloat;
+        merge = mergeOneOption;
+    };
+
     str = mkOptionType {
       name = "str";
       description = "string";