diff --git a/pkgs/development/libraries/openexr/default.nix b/pkgs/development/libraries/openexr/default.nix
index 048d91432b53..1a135fa6d4a8 100644
--- a/pkgs/development/libraries/openexr/default.nix
+++ b/pkgs/development/libraries/openexr/default.nix
@@ -41,11 +41,13 @@ stdenv.mkDerivation rec {
     ./gcc-13.patch
   ];
 
-  # tests are determined to use /var/tmp on unix
   postPatch = ''
+    # tests are determined to use /var/tmp on unix
     find . -name tmpDir.h | while read -r f ; do
       substituteInPlace $f --replace '/var/tmp' "$TMPDIR"
     done
+    # On slower machines this test can take more than the default 1500 seconds
+    echo 'set_tests_properties(OpenEXR.IlmImf PROPERTIES TIMEOUT 3000)' >> OpenEXR/IlmImfTest/CMakeLists.txt
   '';
 
   cmakeFlags = [