diff --git a/dlls/kernel32/heap.c b/dlls/kernel32/heap.c
index 598bfe441e8..db21b7ad8ca 100644
--- a/dlls/kernel32/heap.c
+++ b/dlls/kernel32/heap.c
@@ -1204,17 +1204,17 @@ BOOL WINAPI GlobalMemoryStatusEx( LPMEMORYSTATUSEX lpmemex )
 
             /* new style /proc/meminfo ... */
             if (sscanf(buffer, "MemTotal: %lu", &total))
-                lpmemex->ullTotalPhys = total*1024;
+                lpmemex->ullTotalPhys = (ULONG64)total*1024;
             if (sscanf(buffer, "MemFree: %lu", &free))
-                lpmemex->ullAvailPhys = free*1024;
+                lpmemex->ullAvailPhys = (ULONG64)free*1024;
             if (sscanf(buffer, "SwapTotal: %lu", &total))
-                lpmemex->ullTotalPageFile = total*1024;
+                lpmemex->ullTotalPageFile = (ULONG64)total*1024;
             if (sscanf(buffer, "SwapFree: %lu", &free))
-                lpmemex->ullAvailPageFile = free*1024;
+                lpmemex->ullAvailPageFile = (ULONG64)free*1024;
             if (sscanf(buffer, "Buffers: %lu", &buffers))
-                lpmemex->ullAvailPhys += buffers*1024;
+                lpmemex->ullAvailPhys += (ULONG64)buffers*1024;
             if (sscanf(buffer, "Cached: %lu", &cached))
-                lpmemex->ullAvailPhys += cached*1024;
+                lpmemex->ullAvailPhys += (ULONG64)cached*1024;
         }
         fclose( f );
     }