diff --git a/tools/tests/pdx/test-pdx.c b/tools/tests/pdx/test-pdx.c
index 4de8d43d86..6728ffc7a5 100644
--- a/tools/tests/pdx/test-pdx.c
+++ b/tools/tests/pdx/test-pdx.c
@@ -88,6 +88,22 @@ int main(int argc, char **argv)
             .compress = true,
         },
 #endif
+        /* Range contained in a previous one. */
+        {
+            .ranges = {
+                /* Overlapping ranges. */
+                { .start = 0, .end = (1UL << MAX_ORDER) * 2 },
+                { .start = 0, .end = (1UL << MAX_ORDER) * 1 },
+                /* Extra range to force offset compression to be engaged. */
+                { .start = (1UL << MAX_ORDER) * 3,
+                  .end   = (1UL << MAX_ORDER) * 4 },
+            },
+#ifdef CONFIG_PDX_OFFSET_COMPRESSION
+            .compress = true,
+#else
+            .compress = false,
+#endif
+        },
         /* PDX compression, 2 ranges covered by the lower mask. */
         {
             .ranges = {
diff --git a/xen/common/pdx.c b/xen/common/pdx.c
index e7e16e193e..23655ef3bd 100644
--- a/xen/common/pdx.c
+++ b/xen/common/pdx.c
@@ -393,8 +393,9 @@ bool __init pfn_pdx_compression_setup(paddr_t base)
              (ranges[i - 1].base_pfn + ranges[i - 1].pages) )
             continue;
 
-        ranges[i - 1].pages = ranges[i].base_pfn + ranges[i].pages -
-                              ranges[i - 1].base_pfn;
+        ranges[i - 1].pages = max(ranges[i - 1].pages,
+                                  ranges[i].base_pfn + ranges[i].pages -
+                                  ranges[i - 1].base_pfn);
 
         if ( i + 1 < nr_ranges )
             memmove(&ranges[i], &ranges[i + 1],