diff --git a/lib/deprecated.nix b/lib/deprecated.nix
index 983e8d26892b..d4e78c39250c 100644
--- a/lib/deprecated.nix
+++ b/lib/deprecated.nix
@@ -423,4 +423,12 @@ rec {
       else if isInt x then "int"
       else "string";
 
+  /* deprecated:
+
+     For historical reasons, imap has an index starting at 1.
+
+     But for consistency with the rest of the library we want an index
+     starting at zero.
+  */
+  imap = imap1;
 }
diff --git a/lib/lists.nix b/lib/lists.nix
index fd746f4f97b1..a04b1b278935 100644
--- a/lib/lists.nix
+++ b/lib/lists.nix
@@ -77,15 +77,21 @@ rec {
   */
   foldl' = builtins.foldl' or foldl;
 
-  /* Map with index
-
-     FIXME(zimbatm): why does this start to count at 1?
+  /* Map with index starting from 0
 
      Example:
-       imap (i: v: "${v}-${toString i}") ["a" "b"]
+       imap0 (i: v: "${v}-${toString i}") ["a" "b"]
+       => [ "a-0" "b-1" ]
+  */
+  imap0 = f: list: genList (n: f n (elemAt list n)) (length list);
+
+  /* Map with index starting from 1
+
+     Example:
+       imap1 (i: v: "${v}-${toString i}") ["a" "b"]
        => [ "a-1" "b-2" ]
   */
-  imap = f: list: genList (n: f (n + 1) (elemAt list n)) (length list);
+  imap1 = f: list: genList (n: f (n + 1) (elemAt list n)) (length list);
 
   /* Map and concatenate the result.
 
diff --git a/lib/modules.nix b/lib/modules.nix
index 91e2eae0595e..3da689a6bdb0 100644
--- a/lib/modules.nix
+++ b/lib/modules.nix
@@ -98,7 +98,7 @@ rec {
   /* Close a set of modules under the ‘imports’ relation. */
   closeModules = modules: args:
     let
-      toClosureList = file: parentKey: imap (n: x:
+      toClosureList = file: parentKey: imap1 (n: x:
         if isAttrs x || isFunction x then
           let key = "${parentKey}:anon-${toString n}"; in
           unifyModuleSyntax file key (unpackSubmodule (applyIfFunction key) x args)
diff --git a/lib/strings.nix b/lib/strings.nix
index 1cc633c729dc..a03694d1b1d7 100644
--- a/lib/strings.nix
+++ b/lib/strings.nix
@@ -33,7 +33,7 @@ rec {
        concatImapStrings (pos: x: "${toString pos}-${x}") ["foo" "bar"]
        => "1-foo2-bar"
   */
-  concatImapStrings = f: list: concatStrings (lib.imap f list);
+  concatImapStrings = f: list: concatStrings (lib.imap1 f list);
 
   /* Place an element between each element of a list
 
@@ -70,7 +70,7 @@ rec {
        concatImapStringsSep "-" (pos: x: toString (x / pos)) [ 6 6 6 ]
        => "6-3-2"
   */
-  concatImapStringsSep = sep: f: list: concatStringsSep sep (lib.imap f list);
+  concatImapStringsSep = sep: f: list: concatStringsSep sep (lib.imap1 f list);
 
   /* Construct a Unix-style search path consisting of each `subDir"
      directory of the given list of packages.
diff --git a/lib/types.nix b/lib/types.nix
index 50aa6d770852..a7dcd3f1e1c7 100644
--- a/lib/types.nix
+++ b/lib/types.nix
@@ -179,9 +179,9 @@ rec {
       description = "list of ${elemType.description}s";
       check = isList;
       merge = loc: defs:
-        map (x: x.value) (filter (x: x ? value) (concatLists (imap (n: def:
+        map (x: x.value) (filter (x: x ? value) (concatLists (imap1 (n: def:
           if isList def.value then
-            imap (m: def':
+            imap1 (m: def':
               (mergeDefinitions
                 (loc ++ ["[definition ${toString n}-entry ${toString m}]"])
                 elemType
@@ -220,7 +220,7 @@ rec {
           if isList def.value then
             { inherit (def) file;
               value = listToAttrs (
-                imap (elemIdx: elem:
+                imap1 (elemIdx: elem:
                   { name = elem.name or "unnamed-${toString defIdx}.${toString elemIdx}";
                     value = elem;
                   }) def.value);
@@ -233,7 +233,7 @@ rec {
         name = "loaOf";
         description = "list or attribute set of ${elemType.description}s";
         check = x: isList x || isAttrs x;
-        merge = loc: defs: attrOnly.merge loc (imap convertIfList defs);
+        merge = loc: defs: attrOnly.merge loc (imap1 convertIfList defs);
         getSubOptions = prefix: elemType.getSubOptions (prefix ++ ["<name?>"]);
         getSubModules = elemType.getSubModules;
         substSubModules = m: loaOf (elemType.substSubModules m);
diff --git a/nixos/modules/misc/meta.nix b/nixos/modules/misc/meta.nix
index 6a5738e47ff3..7a1e751394c0 100644
--- a/nixos/modules/misc/meta.nix
+++ b/nixos/modules/misc/meta.nix
@@ -17,7 +17,7 @@ let
     #   }
     merge = loc: defs:
       zipAttrs
-        (flatten (imap (n: def: imap (m: def':
+        (flatten (imap1 (n: def: imap1 (m: def':
           maintainer.merge (loc ++ ["[${toString n}-${toString m}]"])
             [{ inherit (def) file; value = def'; }]) def.value) defs));
   };
diff --git a/nixos/modules/services/cluster/kubernetes.nix b/nixos/modules/services/cluster/kubernetes.nix
index 68917af5094c..4c9d9aad0e2d 100644
--- a/nixos/modules/services/cluster/kubernetes.nix
+++ b/nixos/modules/services/cluster/kubernetes.nix
@@ -44,7 +44,7 @@ let
 
   cniConfig = pkgs.buildEnv {
     name = "kubernetes-cni-config";
-    paths = imap (i: entry:
+    paths = imap1 (i: entry:
       pkgs.writeTextDir "${toString (10+i)}-${entry.type}.conf" (builtins.toJSON entry)
     ) cfg.kubelet.cni.config;
   };
diff --git a/nixos/modules/services/networking/libreswan.nix b/nixos/modules/services/networking/libreswan.nix
index c87e738d2a23..e7a6c565f4ff 100644
--- a/nixos/modules/services/networking/libreswan.nix
+++ b/nixos/modules/services/networking/libreswan.nix
@@ -11,7 +11,7 @@ let
 
   trim = chars: str: let
       nonchars = filter (x : !(elem x.value chars))
-                  (imap (i: v: {ind = (sub i 1); value = v;}) (stringToCharacters str));
+                  (imap0 (i: v: {ind = i; value = v;}) (stringToCharacters str));
     in
       if length nonchars == 0 then ""
       else substring (head nonchars).ind (add 1 (sub (last nonchars).ind (head nonchars).ind)) str;
diff --git a/nixos/modules/services/networking/networkmanager.nix b/nixos/modules/services/networking/networkmanager.nix
index 58c93d8e2ac3..f1b3d298fecb 100644
--- a/nixos/modules/services/networking/networkmanager.nix
+++ b/nixos/modules/services/networking/networkmanager.nix
@@ -253,7 +253,7 @@ in {
            { source = overrideNameserversScript;
              target = "NetworkManager/dispatcher.d/02overridedns";
            }
-      ++ lib.imap (i: s: {
+      ++ lib.imap1 (i: s: {
         inherit (s) source;
         target = "NetworkManager/dispatcher.d/${dispatcherTypesSubdirMap.${s.type}}03userscript${lib.fixedWidthNumber 4 i}";
       }) cfg.dispatcherScripts;
diff --git a/nixos/modules/services/x11/xserver.nix b/nixos/modules/services/x11/xserver.nix
index bb9704fc26f0..638509e710be 100644
--- a/nixos/modules/services/x11/xserver.nix
+++ b/nixos/modules/services/x11/xserver.nix
@@ -71,7 +71,7 @@ let
       name = "multihead${toString num}";
       inherit config;
     };
-  in imap mkHead cfg.xrandrHeads;
+  in imap1 mkHead cfg.xrandrHeads;
 
   xrandrDeviceSection = let
     monitors = flip map xrandrHeads (h: ''
diff --git a/pkgs/games/uqm/default.nix b/pkgs/games/uqm/default.nix
index d6bcb787d60c..d1416b0685a7 100644
--- a/pkgs/games/uqm/default.nix
+++ b/pkgs/games/uqm/default.nix
@@ -18,7 +18,7 @@ let
     inherit stdenv requireFile writeText fetchurl haskellPackages;
   };
 
-  remixPacks = imap (num: sha256: fetchurl rec {
+  remixPacks = imap1 (num: sha256: fetchurl rec {
     name = "uqm-remix-disc${toString num}.uqm";
     url = "mirror://sourceforge/sc2/${name}";
     inherit sha256;