diff --git a/pkgs/build-support/replace-dependencies.nix b/pkgs/build-support/replace-dependencies.nix
index fe325b175fe7..cd97e8b566ed 100644
--- a/pkgs/build-support/replace-dependencies.nix
+++ b/pkgs/build-support/replace-dependencies.nix
@@ -43,7 +43,7 @@ let
   inherit (builtins) unsafeDiscardStringContext appendContext;
   inherit (lib)
     listToAttrs
-    isStorePath
+    isStringLike
     readFile
     attrValues
     mapAttrs
@@ -53,6 +53,16 @@ let
     ;
   inherit (lib.attrsets) mergeAttrsList;
 
+  isNonCaStorePath =
+    x:
+    if isStringLike x then
+      let
+        str = toString x;
+      in
+      builtins.substring 0 1 str == "/" && (dirOf str == builtins.storeDir)
+    else
+      false;
+
   toContextlessString = x: unsafeDiscardStringContext (toString x);
   warn = if verbose then lib.warn else (x: y: y);
 
@@ -90,7 +100,7 @@ let
 
   realisation =
     drv:
-    if isStorePath drv then
+    if isNonCaStorePath drv then
       # Input-addressed and fixed-output derivations have their realisation as outPath.
       toContextlessString drv
     else
diff --git a/pkgs/build-support/replace-direct-dependencies.nix b/pkgs/build-support/replace-direct-dependencies.nix
index 57036ebd74d1..3a51763282e5 100644
--- a/pkgs/build-support/replace-direct-dependencies.nix
+++ b/pkgs/build-support/replace-direct-dependencies.nix
@@ -12,20 +12,30 @@
 }:
 let
   inherit (lib)
-    isStorePath
+    isStringLike
     substring
     stringLength
     optionalString
     escapeShellArgs
     concatMap
     ;
+
+  isNonCaStorePath =
+    x:
+    if isStringLike x then
+      let
+        str = toString x;
+      in
+      builtins.substring 0 1 str == "/" && (dirOf str == builtins.storeDir)
+    else
+      false;
 in
 if replacements == [ ] then
   drv
 else
   let
     drvName =
-      if isStorePath drv then
+      if isNonCaStorePath drv then
         # Reconstruct the name from the actual store path if available.
         substring 33 (stringLength (baseNameOf drv)) (baseNameOf drv)
       else if drv ? drvAttrs.name then