--- a/dom/security/nsCSPContext.cpp
+++ b/dom/security/nsCSPContext.cpp
@@ -34,16 +34,17 @@
 #include "nsNetUtil.h"
 #include "nsIContentPolicy.h"
 #include "nsSupportsPrimitives.h"
 #include "nsThreadUtils.h"
 #include "nsString.h"
 #include "nsScriptSecurityManager.h"
 #include "nsStringStream.h"
 #include "mozilla/Logging.h"
+#include "mozilla/Preferences.h"
 #include "mozilla/dom/CSPReportBinding.h"
 #include "mozilla/dom/CSPDictionariesBinding.h"
 #include "mozilla/net/ReferrerPolicy.h"
 #include "nsINetworkInterceptController.h"
 #include "nsSandboxFlags.h"
 #include "nsIScriptElement.h"
 #include "nsIEventTarget.h"
 #include "mozilla/dom/DocGroup.h"
@@ -266,22 +267,32 @@ NS_IMPL_CLASSINFO(nsCSPContext,
                   nullptr,
                   nsIClassInfo::MAIN_THREAD_ONLY,
                   NS_CSPCONTEXT_CID)
 
 NS_IMPL_ISUPPORTS_CI(nsCSPContext,
                      nsIContentSecurityPolicy,
                      nsISerializable)
 
+int32_t nsCSPContext::sScriptSampleMaxLength;
+
 nsCSPContext::nsCSPContext()
   : mInnerWindowID(0)
   , mLoadingContext(nullptr)
   , mLoadingPrincipal(nullptr)
   , mQueueUpMessages(true)
 {
+  static bool sInitialized = false;
+  if (!sInitialized) {
+    Preferences::AddIntVarCache(&sScriptSampleMaxLength,
+                                "security.csp.reporting.script-sample.max-length",
+                                40);
+    sInitialized = true;
+  }
+
   CSPCONTEXTLOG(("nsCSPContext::nsCSPContext"));
 }
 
 nsCSPContext::~nsCSPContext()
 {
   CSPCONTEXTLOG(("nsCSPContext::~nsCSPContext"));
   for (uint32_t i = 0; i < mPolicies.Length(); i++) {
     delete mPolicies[i];
@@ -474,19 +485,19 @@ nsCSPContext::reportInlineViolation(nsCo
 
   // use selfURI as the sourceFile
   nsAutoCString sourceFile;
   if (mSelfURI) {
     mSelfURI->GetSpec(sourceFile);
   }
 
   nsAutoString codeSample(aContent);
-  // cap the length of the script sample at 40 chars
-  if (codeSample.Length() > 40) {
-    codeSample.Truncate(40);
+  // cap the length of the script sample
+  if (codeSample.Length() > ScriptSampleMaxLength()) {
+    codeSample.Truncate(ScriptSampleMaxLength());
     codeSample.AppendLiteral("...");
   }
   AsyncReportViolation(selfISupports,                      // aBlockedContentSource
                        mSelfURI,                           // aOriginalURI
                        aViolatedDirective,                 // aViolatedDirective
                        aViolatedPolicyIndex,               // aViolatedPolicyIndex
                        observerSubject,                    // aObserverSubject
                        NS_ConvertUTF8toUTF16(sourceFile),  // aSourceFile

--- a/dom/security/nsCSPContext.h
+++ b/dom/security/nsCSPContext.h
@@ -101,16 +101,23 @@ class nsCSPContext : public nsIContentSe
     // helper to report inline script/style violations
     void reportInlineViolation(nsContentPolicyType aContentType,
                                const nsAString& aNonce,
                                const nsAString& aContent,
                                const nsAString& aViolatedDirective,
                                uint32_t aViolatedPolicyIndex,
                                uint32_t aLineNumber);
 
+    static int32_t sScriptSampleMaxLength;
+
+    static uint32_t ScriptSampleMaxLength()
+    {
+      return std::max(sScriptSampleMaxLength, 0);
+    }
+
     nsString                                   mReferrer;
     uint64_t                                   mInnerWindowID; // used for web console logging
     nsTArray<nsCSPPolicy*>                     mPolicies;
     nsCOMPtr<nsIURI>                           mSelfURI;
     nsDataHashtable<nsCStringHashKey, int16_t> mShouldLoadCache;
     nsCOMPtr<nsILoadGroup>                     mCallingChannelLoadGroup;
     nsWeakPtr                                  mLoadingContext;
     // The CSP hangs off the principal, so let's store a raw pointer of the principal