diff --git a/src/arch/generic/decode_cache.hh b/src/arch/generic/decode_cache.hh
index 84f90ca3ef..b4caa72978 100644
--- a/src/arch/generic/decode_cache.hh
+++ b/src/arch/generic/decode_cache.hh
@@ -40,13 +40,13 @@ template <typename Decoder, typename EMI>
 class BasicDecodeCache
 {
   private:
-    DecodeCache::InstMap<EMI> instMap;
+    decode_cache::InstMap<EMI> instMap;
     struct AddrMapEntry
     {
         StaticInstPtr inst;
         EMI machInst;
     };
-    DecodeCache::AddrMap<AddrMapEntry> decodePages;
+    decode_cache::AddrMap<AddrMapEntry> decodePages;
 
   public:
     /// Decode a machine instruction.
diff --git a/src/arch/riscv/decoder.hh b/src/arch/riscv/decoder.hh
index 9b3873db0d..932c4f2639 100644
--- a/src/arch/riscv/decoder.hh
+++ b/src/arch/riscv/decoder.hh
@@ -45,7 +45,7 @@ class ISA;
 class Decoder : public InstDecoder
 {
   private:
-    DecodeCache::InstMap<ExtMachInst> instMap;
+    decode_cache::InstMap<ExtMachInst> instMap;
     bool aligned;
     bool mid;
     bool more;
diff --git a/src/arch/x86/decoder.hh b/src/arch/x86/decoder.hh
index 5bea939e0f..b43cf34b14 100644
--- a/src/arch/x86/decoder.hh
+++ b/src/arch/x86/decoder.hh
@@ -234,14 +234,14 @@ class Decoder : public InstDecoder
 
     typedef RegVal CacheKey;
 
-    typedef DecodeCache::AddrMap<Decoder::InstBytes> DecodePages;
+    typedef decode_cache::AddrMap<Decoder::InstBytes> DecodePages;
     DecodePages *decodePages = nullptr;
     typedef std::unordered_map<CacheKey, DecodePages *> AddrCacheMap;
     AddrCacheMap addrCacheMap;
 
-    DecodeCache::InstMap<ExtMachInst> *instMap = nullptr;
+    decode_cache::InstMap<ExtMachInst> *instMap = nullptr;
     typedef std::unordered_map<
-            CacheKey, DecodeCache::InstMap<ExtMachInst> *> InstCacheMap;
+            CacheKey, decode_cache::InstMap<ExtMachInst> *> InstCacheMap;
     static InstCacheMap instCacheMap;
 
     StaticInstPtr decodeInst(ExtMachInst mach_inst);
@@ -284,7 +284,7 @@ class Decoder : public InstDecoder
         if (imIter != instCacheMap.end()) {
             instMap = imIter->second;
         } else {
-            instMap = new DecodeCache::InstMap<ExtMachInst>;
+            instMap = new decode_cache::InstMap<ExtMachInst>;
             instCacheMap[m5Reg] = instMap;
         }
     }
diff --git a/src/cpu/decode_cache.hh b/src/cpu/decode_cache.hh
index 20b6783d2d..acaa8ca407 100644
--- a/src/cpu/decode_cache.hh
+++ b/src/cpu/decode_cache.hh
@@ -32,9 +32,11 @@
 #include <unordered_map>
 
 #include "base/bitfield.hh"
+#include "base/compiler.hh"
 #include "cpu/static_inst_fwd.hh"
 
-namespace DecodeCache
+GEM5_DEPRECATED_NAMESPACE(DecodeCache, decode_cache);
+namespace decode_cache
 {
 
 /// Hash for decoded instructions.
@@ -131,6 +133,6 @@ class AddrMap
     }
 };
 
-} // namespace DecodeCache
+} // namespace decode_cache
 
 #endif // __CPU_DECODE_CACHE_HH__