diff --git a/cmake/modules/packages/FindECW.cmake b/cmake/modules/packages/FindECW.cmake
index 33e6e848eb2c..6b3624fa9faa 100644
--- a/cmake/modules/packages/FindECW.cmake
+++ b/cmake/modules/packages/FindECW.cmake
@@ -59,13 +59,17 @@ endif()
 include(FindPackageHandleStandardArgs)
 
 if (ECW_VERSION_STRING VERSION_GREATER_EQUAL 5.5)
-    if("${CMAKE_SYSTEM_PROCESSOR}" MATCHES "(x86_64|AMD64)")
-        set(ECW_ARCH x64)
-    else()
-        if(WIN32)
+    if (WIN32)
+        if (CMAKE_SIZEOF_VOID_P EQUAL 4)
             set(ECW_ARCH Win32)
         else()
+            set(ECW_ARCH x64)
+        endif()
+    else()
+        if (CMAKE_SIZEOF_VOID_P EQUAL 4)
             set(ECW_ARCH x86)
+        else()
+            set(ECW_ARCH x64)
         endif()
     endif()