diff --git a/src/openexr.imageio/exrinput.cpp b/src/openexr.imageio/exrinput.cpp
index 3c9933c7bc..39c097ebb2 100644
--- a/src/openexr.imageio/exrinput.cpp
+++ b/src/openexr.imageio/exrinput.cpp
@@ -1139,7 +1139,8 @@ OpenEXRInput::read_native_scanlines(int subimage, int miplevel, int ybegin,
     const PartInfo& part(m_parts[m_subimage]);
     size_t pixelbytes    = m_spec.pixel_bytes(chbegin, chend, true);
     size_t scanlinebytes = (size_t)m_spec.width * pixelbytes;
-    char* buf = (char*)data - m_spec.x * pixelbytes - ybegin * scanlinebytes;
+    char* buf            = (char*)data - m_spec.x * stride_t(pixelbytes)
+                - ybegin * stride_t(scanlinebytes);
 
     try {
         if (part.luminance_chroma) {
diff --git a/src/openexr.imageio/exroutput.cpp b/src/openexr.imageio/exroutput.cpp
index 93894c17d9..f4138cc64a 100644
--- a/src/openexr.imageio/exroutput.cpp
+++ b/src/openexr.imageio/exroutput.cpp
@@ -1516,7 +1516,8 @@ OpenEXROutput::write_scanlines(int ybegin, int yend, int z, TypeDesc format,
         // the bytes to be written, but OpenEXR's frameBuffer.insert() wants
         // where the address of the "virtual framebuffer" for the whole
         // image.
-        char* buf = (char*)d - m_spec.x * pixel_bytes - y * scanlinebytes;
+        char* buf = (char*)d - m_spec.x * stride_t(pixel_bytes)
+                    - y * stride_t(scanlinebytes);
         try {
             Imf::FrameBuffer frameBuffer;
             size_t chanoffset = 0;