diff --git a/src/arch/generic/decode_cache.cc b/src/arch/generic/decode_cache.cc
index 782dfca43f..0f7a9d991b 100644
--- a/src/arch/generic/decode_cache.cc
+++ b/src/arch/generic/decode_cache.cc
@@ -46,7 +46,7 @@ BasicDecodeCache::decode(TheISA::Decoder *decoder,
     if (si && (si->machInst == mach_inst))
         return si;
 
-    DecodeCache::InstMap::iterator iter = instMap.find(mach_inst);
+    auto iter = instMap.find(mach_inst);
     if (iter != instMap.end()) {
         si = iter->second;
         return si;
diff --git a/src/arch/generic/decode_cache.hh b/src/arch/generic/decode_cache.hh
index c6bce72265..ebfaa0645f 100644
--- a/src/arch/generic/decode_cache.hh
+++ b/src/arch/generic/decode_cache.hh
@@ -47,7 +47,7 @@ namespace GenericISA
 class BasicDecodeCache
 {
   private:
-    DecodeCache::InstMap instMap;
+    DecodeCache::InstMap<TheISA::ExtMachInst> instMap;
     DecodeCache::AddrMap<StaticInstPtr> decodePages;
 
   public:
diff --git a/src/arch/riscv/decoder.hh b/src/arch/riscv/decoder.hh
index 91fe7873e2..750321167e 100644
--- a/src/arch/riscv/decoder.hh
+++ b/src/arch/riscv/decoder.hh
@@ -48,7 +48,7 @@ class ISA;
 class Decoder
 {
   private:
-    DecodeCache::InstMap instMap;
+    DecodeCache::InstMap<ExtMachInst> instMap;
     bool aligned;
     bool mid;
     bool more;
diff --git a/src/arch/x86/decoder.cc b/src/arch/x86/decoder.cc
index 835d5e25d2..54701bb730 100644
--- a/src/arch/x86/decoder.cc
+++ b/src/arch/x86/decoder.cc
@@ -681,7 +681,7 @@ Decoder::InstCacheMap Decoder::instCacheMap;
 StaticInstPtr
 Decoder::decode(ExtMachInst mach_inst, Addr addr)
 {
-    DecodeCache::InstMap::iterator iter = instMap->find(mach_inst);
+    auto iter = instMap->find(mach_inst);
     if (iter != instMap->end())
         return iter->second;
 
diff --git a/src/arch/x86/decoder.hh b/src/arch/x86/decoder.hh
index a60aa469ab..3630ea8c8d 100644
--- a/src/arch/x86/decoder.hh
+++ b/src/arch/x86/decoder.hh
@@ -229,8 +229,9 @@ class Decoder
     typedef std::unordered_map<CacheKey, DecodePages *> AddrCacheMap;
     AddrCacheMap addrCacheMap;
 
-    DecodeCache::InstMap *instMap;
-    typedef std::unordered_map<CacheKey, DecodeCache::InstMap *> InstCacheMap;
+    DecodeCache::InstMap<ExtMachInst> *instMap;
+    typedef std::unordered_map<
+            CacheKey, DecodeCache::InstMap<ExtMachInst> *> InstCacheMap;
     static InstCacheMap instCacheMap;
 
   public:
@@ -277,7 +278,7 @@ class Decoder
         if (imIter != instCacheMap.end()) {
             instMap = imIter->second;
         } else {
-            instMap = new DecodeCache::InstMap;
+            instMap = new DecodeCache::InstMap<ExtMachInst>;
             instCacheMap[m5Reg] = instMap;
         }
     }
diff --git a/src/cpu/decode_cache.hh b/src/cpu/decode_cache.hh
index c451cbb699..2d33455e04 100644
--- a/src/cpu/decode_cache.hh
+++ b/src/cpu/decode_cache.hh
@@ -47,7 +47,8 @@ namespace DecodeCache
 {
 
 /// Hash for decoded instructions.
-typedef std::unordered_map<TheISA::ExtMachInst, StaticInstPtr> InstMap;
+template <typename EMI>
+using InstMap = std::unordered_map<EMI, StaticInstPtr>;
 
 /// A sparse map from an Addr to a Value, stored in page chunks.
 template<class Value>