diff --git a/src/pipewire/mem.c b/src/pipewire/mem.c
index 1fa371247..642a6b78e 100644
--- a/src/pipewire/mem.c
+++ b/src/pipewire/mem.c
@@ -393,7 +393,6 @@ struct pw_memmap * pw_memblock_map(struct pw_memblock *block,
 	struct mempool *p = SPA_CONTAINER_OF(block->pool, struct mempool, this);
 	struct mapping *m;
 	struct memmap *mm;
-	struct pw_map_range range;
 	struct stat sb;
 
 	if (b->this.fd == -1) {
@@ -418,13 +417,15 @@ struct pw_memmap * pw_memblock_map(struct pw_memblock *block,
 		return NULL;
 	}
 
-	pw_map_range_init(&range, offset, size, p->pagesize);
-
 	m = memblock_find_mapping(b, flags, offset, size);
-	if (m == NULL)
+	if (m == NULL) {
+		struct pw_map_range range;
+		pw_map_range_init(&range, offset, size, p->pagesize);
+
 		m = memblock_map(b, flags, range.offset, range.size);
-	if (m == NULL)
-		return NULL;
+		if (m == NULL)
+			return NULL;
+	}
 
 	mm = calloc(1, sizeof(struct memmap));
 	if (mm == NULL) {
@@ -439,7 +440,7 @@ struct pw_memmap * pw_memblock_map(struct pw_memblock *block,
 	mm->this.flags = flags;
 	mm->this.offset = offset;
 	mm->this.size = size;
-	mm->this.ptr = SPA_PTROFF(m->ptr, range.start, void);
+	mm->this.ptr = SPA_PTROFF(m->ptr, offset - m->offset, void);
 
         pw_log_debug("%p: map:%p block:%p fd:%d flags:%08x ptr:%p (%u %u) mapping:%p ref:%d", p,
 			&mm->this, b, b->this.fd, b->this.flags, mm->this.ptr, offset, size, m, m->ref);
diff --git a/test/meson.build b/test/meson.build
index 43a59a254..7c0a4d574 100644
--- a/test/meson.build
+++ b/test/meson.build
@@ -53,6 +53,7 @@ test('test-pw-utils',
                'test-properties.c',
                'test-array.c',
                'test-map.c',
+               'test-mempool.c',
                'test-utils.c',
                include_directories: pwtest_inc,
                dependencies: [ spa_dep ],
diff --git a/test/test-mempool.c b/test/test-mempool.c
new file mode 100644
index 000000000..36f69c571
--- /dev/null
+++ b/test/test-mempool.c
@@ -0,0 +1,49 @@
+/* PipeWire */
+/* SPDX-FileCopyrightText: Copyright © 2025 PipeWire authors */
+/* SPDX-License-Identifier: MIT */
+
+#include <unistd.h>
+
+#include <pipewire/mem.h>
+#include <spa/buffer/buffer.h>
+
+#include "pwtest.h"
+
+PWTEST(mempool_issue4884)
+{
+	/*
+	 * See https://gitlab.freedesktop.org/pipewire/pipewire/-/issues/4884. This
+	 * test checks if the offset is correctly applied when a mapping is reused.
+	 */
+
+	long page_size = sysconf(_SC_PAGESIZE);
+	pwtest_errno_ok(page_size);
+	pwtest_int_ge(page_size, 8);
+
+	struct pw_mempool *p = pw_mempool_new(NULL);
+	pwtest_ptr_notnull(p);
+
+	struct pw_memblock *b = pw_mempool_alloc(p, PW_MEMBLOCK_FLAG_READWRITE, SPA_DATA_MemFd, 2 * page_size);
+	pwtest_ptr_notnull(b);
+
+	struct pw_memmap *m1 = pw_mempool_map_id(p, b->id, PW_MEMMAP_FLAG_READWRITE, page_size / 2, page_size, NULL);
+	pwtest_ptr_notnull(m1);
+	pwtest_ptr_eq(m1->block, b);
+
+	struct pw_memmap *m2 = pw_mempool_map_id(p, b->id, PW_MEMMAP_FLAG_READWRITE, 3 * page_size / 2, page_size / 2, NULL);
+	pwtest_ptr_notnull(m2);
+	pwtest_ptr_eq(m2->block, b);
+
+	pwtest_int_eq(SPA_PTRDIFF(m2->ptr, m1->ptr), page_size);
+
+	pw_mempool_destroy(p);
+
+	return PWTEST_PASS;
+}
+
+PWTEST_SUITE(pw_mempool)
+{
+	pwtest_add(mempool_issue4884, PWTEST_NOARG);
+
+	return PWTEST_PASS;
+}