diff --git a/osc.c b/osc.c
index 9c3b326a..94b6892c 100644
--- a/osc.c
+++ b/osc.c
@@ -902,11 +902,20 @@ osc_dispatch(struct terminal *term)
 bool
 osc_ensure_size(struct terminal *term, size_t required_size)
 {
-    if (required_size <= term->vt.osc.size)
+    if (likely(required_size <= term->vt.osc.size))
         return true;
 
-    size_t new_size = (required_size + 127) / 128 * 128;
-    xassert(new_size > 0);
+    const size_t pow2_max = ~(SIZE_MAX >> 1);
+    if (unlikely(required_size > pow2_max)) {
+        LOG_ERR("required OSC buffer size (%zu) exceeds limit (%zu)",
+            required_size, pow2_max);
+        return false;
+    }
+
+    size_t new_size = max(term->vt.osc.size, 4096);
+    while (new_size < required_size) {
+        new_size <<= 1;
+    }
 
     uint8_t *new_data = realloc(term->vt.osc.data, new_size);
     if (new_data == NULL) {
@@ -914,6 +923,7 @@ osc_ensure_size(struct terminal *term, size_t required_size)
         return false;
     }
 
+    LOG_DBG("resized OSC buffer: %zu", new_size);
     term->vt.osc.data = new_data;
     term->vt.osc.size = new_size;
     return true;