diff --git a/include/xrpl/basics/base_uint.h b/include/xrpl/basics/base_uint.h
index 93df24ec63..8c8c568a19 100644
--- a/include/xrpl/basics/base_uint.h
+++ b/include/xrpl/basics/base_uint.h
@@ -323,6 +323,8 @@ public:
             "xrpl::BaseUInt::operator=(Container auto) : input size match");
         std::size_t const canCopy =
             std::min(size(), c.size() * sizeof(typename Container::value_type));
+        if (canCopy < size())
+            *this = beast::kZero;
         std::memcpy(data_.data(), c.data(), canCopy);
         return *this;
     }
diff --git a/src/test/protocol/STIssue_test.cpp b/src/test/protocol/STIssue_test.cpp
index 5f9c275037..b7cc944e6b 100644
--- a/src/test/protocol/STIssue_test.cpp
+++ b/src/test/protocol/STIssue_test.cpp
@@ -175,8 +175,8 @@ public:
         auto const result = env.rpc("json", "sign", to_string(req))[jss::result];
 
         BEAST_EXPECT(result[jss::error] == "invalidParams");
-        BEAST_EXPECT(
-            result[jss::error_message] == "Field 'tx_json.Asset' has invalid data.");
+        BEAST_EXPECT(result[jss::error_message] == "Field 'tx_json.Asset' has invalid data.");
+    }
 
     void
     testNoAccountIssuer()
@@ -248,8 +248,8 @@ public:
         auto const result = env.rpc("json", "sign", to_string(req))[jss::result];
 
         BEAST_EXPECT(result[jss::error] == "invalidParams");
-        BEAST_EXPECT(
-            result[jss::error_message] == "Field 'tx_json.Asset' has invalid data.");
+        BEAST_EXPECT(result[jss::error_message] == "Field 'tx_json.Asset' has invalid data.");
+    }
 
     void
     testXrpAccountIssuer()
diff --git a/src/tests/libxrpl/basics/base_uint_test.cpp b/src/tests/libxrpl/basics/base_uint_test.cpp
index 5777b73754..4972c86e19 100644
--- a/src/tests/libxrpl/basics/base_uint_test.cpp
+++ b/src/tests/libxrpl/basics/base_uint_test.cpp
@@ -136,7 +136,7 @@ TEST_F(BaseUintDeathTest, fromRaw_size_mismatch)
             auto const resultText = to_string(result);
             EXPECT_EQ(resultText, "010203040506070800000000") << resultText;
         }),
-        "xrpl::BaseUInt::fromRaw(Container auto) : input size match");
+        "input size match");
 
     EXPECT_DEBUG_DEATH(
         ({
@@ -148,7 +148,43 @@ TEST_F(BaseUintDeathTest, fromRaw_size_mismatch)
             auto const resultText = to_string(result);
             EXPECT_EQ(resultText, "0102030405060708090A0B0C") << resultText;
         }),
-        "xrpl::BaseUInt::fromRaw(Container auto) : input size match");
+        "input size match");
+
+    EXPECT_DEBUG_DEATH(
+        ({
+            // Container smaller than the base_uint (8 bytes vs 12 bytes for
+            // test96). Only the first 8 bytes are copied; the remaining 4 bytes
+            // stay zero.
+            Blob const tooSmall{1, 2, 3, 4, 5, 6, 7, 8};
+            BaseUInt96 result{};
+            --result;
+            {
+                auto const originalText = to_string(result);
+                EXPECT_EQ(originalText, "FFFFFFFFFFFFFFFFFFFFFFFF") << originalText;
+            }
+            result = tooSmall;
+            auto const resultText = to_string(result);
+            EXPECT_EQ(resultText, "010203040506070800000000") << resultText;
+        }),
+        "input size match");
+
+    EXPECT_DEBUG_DEATH(
+        ({
+            // Container larger than the base_uint (16 bytes vs 12 bytes for
+            // test96). Only the first 12 bytes are copied; the extra bytes are
+            // ignored.
+            Blob const tooBig{1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16};
+            BaseUInt96 result{};
+            --result;
+            {
+                auto const originalText = to_string(result);
+                EXPECT_EQ(originalText, "FFFFFFFFFFFFFFFFFFFFFFFF") << originalText;
+            }
+            result = tooBig;
+            auto const resultText = to_string(result);
+            EXPECT_EQ(resultText, "0102030405060708090A0B0C") << resultText;
+        }),
+        "input size match");
 }
 
 TEST_F(BaseUintTest, base_uint)