diff --git a/fpga/tangnano20k/tangnano20k.gprj.user b/fpga/tangnano20k/tangnano20k.gprj.user
index 76df23e..375705c 100644
--- a/fpga/tangnano20k/tangnano20k.gprj.user
+++ b/fpga/tangnano20k/tangnano20k.gprj.user
@@ -4,8 +4,8 @@
     <Version>1.0</Version>
     <FlowState>
         <Process ID="Synthesis" State="2"/>
-        <Process ID="Pnr" State="2"/>
-        <Process ID="Gao" State="2"/>
+        <Process ID="Pnr" State="4"/>
+        <Process ID="Gao" State="4"/>
         <Process ID="Rtl_Gao" State="2"/>
     </FlowState>
     <ResultFileList>
@@ -20,5 +20,5 @@
         <ResultFile ResultFileType="RES.syn.report" ResultFilePath="impl/gwsynthesis/tangnano20k_syn.rpt.html"/>
         <ResultFile ResultFileType="RES.syn.resource" ResultFilePath="impl/gwsynthesis/tangnano20k_syn_rsc.xml"/>
     </ResultFileList>
-    <Ui>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</Ui>
+    <Ui>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</Ui>
 </UserConfig>
diff --git a/src/peripheral/fifo.v b/src/peripheral/fifo.v
index 43d4fa9..d40fc29 100644
--- a/src/peripheral/fifo.v
+++ b/src/peripheral/fifo.v
@@ -9,7 +9,7 @@ module FIFO #(
     input wire [WIDTH-1:0] write_data,
     output wire full,
     output wire empty,
-    output reg [WIDTH-1:0] read_data
+    output wire [WIDTH-1:0] read_data
 );
 
 reg [WIDTH-1:0] memory[DEPTH-1:0];