diff --git a/libwvdrmengine/mediacrypto/include/WVCryptoPlugin.h b/libwvdrmengine/mediacrypto/include/WVCryptoPlugin.h
index 9d51a225..ee035864 100644
--- a/libwvdrmengine/mediacrypto/include/WVCryptoPlugin.h
+++ b/libwvdrmengine/mediacrypto/include/WVCryptoPlugin.h
@@ -50,8 +50,6 @@ class WVCryptoPlugin : public android::CryptoPlugin {
   android::status_t attemptDecrypt(
       const wvcdm::CdmDecryptionParameters& params,
       bool haveEncryptedSubsamples, android::AString* errorDetailMsg);
-  static wvcdm::CdmResponseType countEncryptedBlocksInPatternedRange(
-      size_t range, const Pattern& pattern, uint64_t* result);
   static void incrementIV(uint64_t increaseBy, std::vector<uint8_t>* ivPtr);
 };
 
diff --git a/libwvdrmengine/mediacrypto/include_hidl/WVCryptoPlugin.h b/libwvdrmengine/mediacrypto/include_hidl/WVCryptoPlugin.h
index c020bc7e..a7570731 100644
--- a/libwvdrmengine/mediacrypto/include_hidl/WVCryptoPlugin.h
+++ b/libwvdrmengine/mediacrypto/include_hidl/WVCryptoPlugin.h
@@ -72,8 +72,6 @@ struct WVCryptoPlugin : public ICryptoPlugin {
     Status_V1_2 attemptDecrypt(
       const wvcdm::CdmDecryptionParameters& params,
       bool haveEncryptedSubsamples, std::string* errorDetailMsg);
-  static wvcdm::CdmResponseType countEncryptedBlocksInPatternedRange(
-      size_t range, const Pattern& pattern, uint64_t* result);
   static void incrementIV(uint64_t increaseBy, std::vector<uint8_t>* ivPtr);
 };
 
diff --git a/libwvdrmengine/mediacrypto/src/WVCryptoPlugin.cpp b/libwvdrmengine/mediacrypto/src/WVCryptoPlugin.cpp
index ee72cc32..ec9005b6 100644
--- a/libwvdrmengine/mediacrypto/src/WVCryptoPlugin.cpp
+++ b/libwvdrmengine/mediacrypto/src/WVCryptoPlugin.cpp
@@ -234,12 +234,16 @@ ssize_t WVCryptoPlugin::decrypt(bool secure, const uint8_t key[KEY_ID_SIZE],
           increment = (blockOffset + subSample.mNumBytesOfEncryptedData) /
               kAESBlockSize;
         } else {
-          CdmResponseType countRes = countEncryptedBlocksInPatternedRange(
-              subSample.mNumBytesOfEncryptedData, pattern, &increment);
-          if (!isCdmResponseTypeSuccess(countRes)) {
-            // Swallow the specifics of the error to obscure decrypt internals.
-            return kErrorCDMGeneric;
-          }
+          const uint64_t numBlocks =
+              subSample.mNumBytesOfEncryptedData / kAESBlockSize;
+          const uint64_t patternLengthInBlocks =
+              pattern.mEncryptBlocks + pattern.mSkipBlocks;
+          increment =
+              (numBlocks / patternLengthInBlocks) * pattern.mEncryptBlocks;
+          // A partial pattern is only encrypted if it is at least
+          // mEncryptBlocks large.
+          if (numBlocks % patternLengthInBlocks >= pattern.mEncryptBlocks)
+            increment += pattern.mEncryptBlocks;
         }
         incrementIV(increment, &ivVector);
 
@@ -348,26 +352,6 @@ status_t WVCryptoPlugin::attemptDecrypt(const CdmDecryptionParameters& params,
   }
 }
 
-CdmResponseType WVCryptoPlugin::countEncryptedBlocksInPatternedRange(
-    size_t range, const Pattern& pattern, uint64_t* result) {
-  if (result == NULL || range % kAESBlockSize != 0) {
-    return wvcdm::UNKNOWN_ERROR;
-  }
-
-  const size_t patternLength = pattern.mEncryptBlocks + pattern.mSkipBlocks;
-  uint64_t encryptedBlocksPassed = 0;
-  size_t patternPosition = 0;
-  for (size_t remaining = range / kAESBlockSize; remaining > 0; --remaining) {
-    if (patternPosition < pattern.mEncryptBlocks) {
-      ++encryptedBlocksPassed;
-    }
-    patternPosition = (patternPosition + 1) % patternLength;
-  }
-
-  *result = encryptedBlocksPassed;
-  return wvcdm::NO_ERROR;
-}
-
 void WVCryptoPlugin::incrementIV(uint64_t increaseBy, vector<uint8_t>* ivPtr) {
   vector<uint8_t>& iv = *ivPtr;
   uint64_t* counterBuffer = reinterpret_cast<uint64_t*>(&iv[8]);
diff --git a/libwvdrmengine/mediacrypto/src_hidl/WVCryptoPlugin.cpp b/libwvdrmengine/mediacrypto/src_hidl/WVCryptoPlugin.cpp
index 8ccb3da5..36aa7ce3 100644
--- a/libwvdrmengine/mediacrypto/src_hidl/WVCryptoPlugin.cpp
+++ b/libwvdrmengine/mediacrypto/src_hidl/WVCryptoPlugin.cpp
@@ -338,14 +338,16 @@ Return<void> WVCryptoPlugin::decrypt_1_2(
           increment = (blockOffset + subSample.numBytesOfEncryptedData) /
               kAESBlockSize;
         } else {
-          CdmResponseType countRes = countEncryptedBlocksInPatternedRange(
-              subSample.numBytesOfEncryptedData, pattern, &increment);
-          if (!isCdmResponseTypeSuccess(countRes)) {
-            // Swallow the specifics of the error to obscure decrypt internals.
-            _hidl_cb(Status_V1_2::ERROR_DRM_CANNOT_HANDLE, 0,
-                     "Error decrypting data: unknown error");
-            return Void();
-          }
+          const uint64_t numBlocks =
+              subSample.numBytesOfEncryptedData / kAESBlockSize;
+          const uint64_t patternLengthInBlocks =
+              pattern.encryptBlocks + pattern.skipBlocks;
+          increment =
+              (numBlocks / patternLengthInBlocks) * pattern.encryptBlocks;
+          // A partial pattern is only encrypted if it is at least
+          // mEncryptBlocks large.
+          if (numBlocks % patternLengthInBlocks >= pattern.encryptBlocks)
+            increment += pattern.encryptBlocks;
         }
         incrementIV(increment, &ivVector);
 
@@ -429,26 +431,6 @@ Status_V1_2 WVCryptoPlugin::attemptDecrypt(const CdmDecryptionParameters& params
   }
 }
 
-CdmResponseType WVCryptoPlugin::countEncryptedBlocksInPatternedRange(
-    size_t range, const Pattern& pattern, uint64_t* result) {
-  if (result == NULL || range % kAESBlockSize != 0) {
-    return wvcdm::UNKNOWN_ERROR;
-  }
-
-  const size_t patternLength = pattern.encryptBlocks + pattern.skipBlocks;
-  uint64_t encryptedBlocksPassed = 0;
-  size_t patternPosition = 0;
-  for (size_t remaining = range / kAESBlockSize; remaining > 0; --remaining) {
-    if (patternPosition < pattern.encryptBlocks) {
-      ++encryptedBlocksPassed;
-    }
-    patternPosition = (patternPosition + 1) % patternLength;
-  }
-
-  *result = encryptedBlocksPassed;
-  return wvcdm::NO_ERROR;
-}
-
 void WVCryptoPlugin::incrementIV(uint64_t increaseBy,
                                  std::vector<uint8_t>* ivPtr) {
   std::vector<uint8_t>& iv = *ivPtr;