https://github.com/ImageMagick/ImageMagick/issues/1134

diff --git a/MagickCore/opencl.c b/MagickCore/opencl.c
index dc59e7dad7fb49f6896edc7850d47df831f381f1..d5530e650d19c45ac16b08fdaf7caaacea6b1ad9 100644 (file)
--- a/MagickCore/opencl.c
+++ b/MagickCore/opencl.c
@@ -3000,7 +3000,7 @@ static MagickCLEnv RelinquishMagickCLEnv(MagickCLEnv clEnv)
         i;
 
       for (i=0; i < clEnv->number_contexts; i++)
-        if (clEnv->contexts[i])
+        if (clEnv->contexts[i] != (cl_context) NULL)
           (void) openCL_library->clReleaseContext(clEnv->contexts[i]);
       clEnv->contexts=(cl_context *) RelinquishMagickMemory(clEnv->contexts);
     }