diff --git a/src/peakrdl_busdecoder/cpuif/apb4/apb4_cpuif_flat.py b/src/peakrdl_busdecoder/cpuif/apb4/apb4_cpuif_flat.py
index ddbac6e..56ed87f 100644
--- a/src/peakrdl_busdecoder/cpuif/apb4/apb4_cpuif_flat.py
+++ b/src/peakrdl_busdecoder/cpuif/apb4/apb4_cpuif_flat.py
@@ -42,7 +42,7 @@ class APB4CpuifFlat(BaseCpuif):
         fanout[self.signal("PWRITE", node, "gi")] = (
             f"cpuif_wr_sel.{get_indexed_path(self.exp.ds.top_node, node, 'gi')}"
         )
-        fanout[self.signal("PADDR", node, "gi")] = f'{self.signal("PADDR")}[{clog2(node.size) - 1}:0]'
+        fanout[self.signal("PADDR", node, "gi")] = f"{self.signal('PADDR')}[{clog2(node.size) - 1}:0]"
         fanout[self.signal("PPROT", node, "gi")] = self.signal("PPROT")
         fanout[self.signal("PWDATA", node, "gi")] = "cpuif_wr_data"
         fanout[self.signal("PSTRB", node, "gi")] = "cpuif_wr_byte_en"