diff --git a/pkgs/development/libraries/science/math/cudnn/extension.nix b/pkgs/development/libraries/science/math/cudnn/extension.nix
index 01ec5e4b9b5d..fae958c31d17 100644
--- a/pkgs/development/libraries/science/math/cudnn/extension.nix
+++ b/pkgs/development/libraries/science/math/cudnn/extension.nix
@@ -111,6 +111,6 @@ final: prev: let
     "11.4" = "8.3.2";
     "11.5" = "8.3.2";
     "11.6" = "8.3.2";
-  }.${cudaVersion};
+  }.${cudaVersion} or "8.3.2";
 
 in cuDnnPackages
diff --git a/pkgs/development/libraries/science/math/tensorrt/extension.nix b/pkgs/development/libraries/science/math/tensorrt/extension.nix
index 8e9f64885bad..b76d35a0d84f 100644
--- a/pkgs/development/libraries/science/math/tensorrt/extension.nix
+++ b/pkgs/development/libraries/science/math/tensorrt/extension.nix
@@ -58,6 +58,6 @@ final: prev: let
     "11.4" = "8.4.0";
     "11.5" = "8.4.0";
     "11.6" = "8.4.0";
-  }.${cudaVersion};
+  }.${cudaVersion} or "8.4.0";
 
 in tensorRTPackages