diff --git a/src/cubeb_resampler_internal.h b/src/cubeb_resampler_internal.h
index 3e8b097..876d09b 100644
--- a/src/cubeb_resampler_internal.h
+++ b/src/cubeb_resampler_internal.h
@@ -307,9 +307,11 @@ public:
   uint32_t input_needed_for_output(int32_t output_frame_count) const
   {
     assert(output_frame_count >= 0); // Check overflow
+    int32_t unresampled_frames_left = samples_to_frames(resampling_in_buffer.length());
     int32_t resampled_frames_left = samples_to_frames(resampling_out_buffer.length());
-    float input_frames_needed = 
-      output_frame_count * resampling_ratio - resampled_frames_left;
+    float input_frames_needed =
+      (output_frame_count - unresampled_frames_left) * resampling_ratio
+        - resampled_frames_left;
     if (input_frames_needed < 0) {
       return 0;
     }