diff --git a/src/ram.c b/src/ram.c
index 699d067..a41ef3b 100644
--- a/src/ram.c
+++ b/src/ram.c
@@ -282,7 +282,11 @@ ram_alloc_buffer(struct ppn *ppn_out, struct ram_buffer_requirements req)
         TODO();
     }
 
-    unsigned magnitude = next_pow2(req.size);
+    if (req.size < 4096) {
+        req.size = 4096;
+    }
+    uint64_t next_size = next_pow2(req.size);
+    unsigned magnitude = __builtin_ffsl(next_size) - 1 - 12;
 
     uint64_t addr;
     if (!alloc_block(&addr, magnitude)) {