diff --git a/tools/valgrind/memcheck/suppressions_mac.txt b/tools/valgrind/memcheck/suppressions_mac.txt
index 670b36f020327c2dce48ae5e182e8bdc82ecf46a..820677e8606e6508c785d503ba18917cd24b7e82 100644
--- a/tools/valgrind/memcheck/suppressions_mac.txt
+++ b/tools/valgrind/memcheck/suppressions_mac.txt
@@ -986,6 +986,23 @@
    fun:_ZL17cssm_DataGetFirst17cssm_dl_db_handlePK10cssm_queryPlP29cssm_db_record_attribute_dataP9cssm_dataPP21cssm_db_unique_record
    fun:CSSM_DL_DataGetFirst
 }
+{
+   bug_51682c
+   Memcheck:Leak
+   fun:realloc
+   fun:_ZN16DefaultAllocator7reallocEPvm
+   fun:_ZN8Security28CssmAllocatorMemoryFunctions12relayReallocEPvmS1_
+   fun:_ZNK8Security19CssmMemoryFunctions7reallocEPvm
+   fun:_ZN8Security28CssmMemoryFunctionsAllocator7reallocEPvm
+   fun:_ZN10Attachment13upcallReallocElPvj
+   fun:_ZN8Security13PluginSession7reallocEPvm
+   fun:_ZN17DecodedExtensions12addExtensionERK9cssm_databPvbPK22SecAsn1Template_structPS1_
+   fun:_ZN17DecodedExtensions13decodeFromNssEPP17NSS_CertExtension
+   fun:_ZN11DecodedCertC2ER18AppleX509CLSessionRKN8Security8CssmDataE
+   fun:_ZN18AppleX509CLSession22CertGetFirstFieldValueERKN8Security8CssmDataES3_RjRP9cssm_data
+   fun:_Z27cssm_CertGetFirstFieldValuelPK9cssm_dataS1_PlPjPPS_
+   fun:CSSM_CL_CertGetFirstFieldValue
+}
 {
    bug_60873
    Memcheck:Cond