diff --git a/libqpdf/Pl_MD5.cc b/libqpdf/Pl_MD5.cc
index a5985a9..5cf5dba 100644
--- a/libqpdf/Pl_MD5.cc
+++ b/libqpdf/Pl_MD5.cc
@@ -2,14 +2,6 @@
 
 #include <stdexcept>
 
-Pl_MD5::Pl_MD5(char const* identifier, Pipeline* next) :
-    Pipeline(identifier, next)
-{
-    if (!next) {
-        throw std::logic_error("Attempt to create Pl_MD5 with nullptr as next");
-    }
-}
-
 void
 Pl_MD5::write(unsigned char const* buf, size_t len)
 {
@@ -31,36 +23,7 @@ Pl_MD5::write(unsigned char const* buf, size_t len)
         }
     }
 
-    next()->write(buf, len);
-}
-
-void
-Pl_MD5::finish()
-{
-    next()->finish();
-    if (!persist_across_finish) {
-        in_progress = false;
-    }
-}
-
-void
-Pl_MD5::enable(bool is_enabled)
-{
-    enabled = is_enabled;
-}
-
-void
-Pl_MD5::persistAcrossFinish(bool persist)
-{
-    persist_across_finish = persist;
-}
-
-std::string
-Pl_MD5::getHexDigest()
-{
-    if (!enabled) {
-        throw std::logic_error("digest requested for a disabled MD5 Pipeline");
+    if (next()) {
+        next()->write(buf, len);
     }
-    in_progress = false;
-    return md5.unparse();
 }
diff --git a/libqpdf/qpdf/Pl_MD5.hh b/libqpdf/qpdf/Pl_MD5.hh
index 31ae263..37c9380 100644
--- a/libqpdf/qpdf/Pl_MD5.hh
+++ b/libqpdf/qpdf/Pl_MD5.hh
@@ -4,6 +4,8 @@
 #include <qpdf/MD5.hh>
 #include <qpdf/Pipeline.hh>
 
+#include <stdexcept>
+
 // This pipeline sends its output to its successor unmodified.  After calling finish, the MD5
 // checksum of the data that passed through the pipeline is available.
 
@@ -12,18 +14,47 @@
 class Pl_MD5 final: public Pipeline
 {
   public:
-    Pl_MD5(char const* identifier, Pipeline* next);
+    Pl_MD5(char const* identifier, Pipeline* next = nullptr) :
+        Pipeline(identifier, next)
+    {
+    }
+
     ~Pl_MD5() final = default;
     void write(unsigned char const*, size_t) final;
-    void finish() final;
-    std::string getHexDigest();
+    void
+    finish() final
+    {
+        if (next()) {
+            next()->finish();
+        }
+        if (!persist_across_finish) {
+            in_progress = false;
+        }
+    }
+    std::string
+    getHexDigest()
+    {
+        if (!enabled) {
+            throw std::logic_error("digest requested for a disabled MD5 Pipeline");
+        }
+        in_progress = false;
+        return md5.unparse();
+    }
     // Enable/disable. Disabling the pipeline causes it to become a pass-through. This makes it
     // possible to stick an MD5 pipeline in a pipeline when it may or may not be required. Disabling
     // it avoids incurring the runtime overhead of doing needless digest computation.
-    void enable(bool enabled);
+    void
+    enable(bool val)
+    {
+        enabled = val;
+    }
     // If persistAcrossFinish is called, calls to finish do not finalize the underlying md5 object.
     // In this case, the object is not finalized until getHexDigest() is called.
-    void persistAcrossFinish(bool);
+    void
+    persistAcrossFinish(bool val)
+    {
+        persist_across_finish = val;
+    }
 
   private:
     bool in_progress{false};