diff --git a/ipmi.cpp b/ipmi.cpp
index 6201f0e..5752682 100644
--- a/ipmi.cpp
+++ b/ipmi.cpp
@@ -15,19 +15,37 @@
  */
 
 #include <cstring>
+#include <unordered_map>
 
 #include "flash-ipmi.hpp"
 #include "ipmi.hpp"
 
+bool validateRequestLength(FlashSubCmds command, size_t requestLen)
+{
+    static const std::unordered_map<FlashSubCmds, size_t> minimumLengths = {
+        {FlashSubCmds::flashStartTransfer, sizeof(struct StartTx)},
+        {FlashSubCmds::flashDataBlock, sizeof(struct ChunkHdr) + 1},
+    };
+
+    auto results = minimumLengths.find(command);
+    if (results == minimumLengths.end())
+    {
+        /* Valid length by default if we don't care. */
+        return true;
+    }
+
+    /* If the request is shorter than the minimum, it's invalid. */
+    if (requestLen < results->second)
+    {
+        return false;
+    }
+
+    return true;
+}
+
 ipmi_ret_t startTransfer(UpdateInterface* updater, const uint8_t* reqBuf,
                          uint8_t* replyBuf, size_t* dataLen)
 {
-    /* Validate the request buffer. */
-    if (sizeof(struct StartTx) > (*dataLen))
-    {
-        return IPMI_CC_INVALID;
-    }
-
     auto request = reinterpret_cast<const struct StartTx*>(reqBuf);
 
     if (!updater->start(request->length))
@@ -44,16 +62,11 @@
 ipmi_ret_t dataBlock(UpdateInterface* updater, const uint8_t* reqBuf,
                      uint8_t* replyBuf, size_t* dataLen)
 {
-    size_t requestLength = (*dataLen);
-    /* Require at least one byte. */
-    if (requestLength < sizeof(struct ChunkHdr) + 1)
-    {
-        return IPMI_CC_INVALID;
-    }
-
     struct ChunkHdr hdr;
     std::memcpy(&hdr, reqBuf, sizeof(hdr));
 
+    size_t requestLength = (*dataLen);
+
     /* Grab the bytes from the packet. */
     size_t bytesLength = requestLength - sizeof(struct ChunkHdr);
     std::vector<uint8_t> bytes(bytesLength);
diff --git a/ipmi.hpp b/ipmi.hpp
index dcaf33e..0644ad8 100644
--- a/ipmi.hpp
+++ b/ipmi.hpp
@@ -5,6 +5,15 @@
 #include "flash-ipmi.hpp"
 
 /**
+ * Validate the minimum request length if there is one.
+ *
+ * @param[in] subcommand - the command
+ * @param[in] requestLength - the length of the request
+ * @return bool - true if valid.
+ */
+bool validateRequestLength(FlashSubCmds command, size_t requestLen);
+
+/**
  * Prepare to receive a BMC image and then a signature.
  *
  * @param[in] updater - Pointer to Updater object.
diff --git a/main.cpp b/main.cpp
index 9b78f77..7a22923 100644
--- a/main.cpp
+++ b/main.cpp
@@ -44,7 +44,13 @@
         return IPMI_CC_INVALID;
     }
 
-    uint8_t subCmd = reqBuf[0];
+    auto subCmd = static_cast<FlashSubCmds>(reqBuf[0]);
+
+    /* Validate the minimum request length for the command. */
+    if (!validateRequestLength(subCmd, *dataLen))
+    {
+        return IPMI_CC_INVALID;
+    }
 
     /* TODO: This could be cleaner to just have a function pointer table, may
      * transition in later patchset.
diff --git a/test/Makefile.am b/test/Makefile.am
index d9fd289..9df14db 100644
--- a/test/Makefile.am
+++ b/test/Makefile.am
@@ -11,7 +11,8 @@
 # Run all 'check' test programs
 check_PROGRAMS = \
 	ipmi_starttransfer_unittest \
-	ipmi_flashdata_unittest
+	ipmi_flashdata_unittest \
+	ipmi_validate_unittest
 
 TESTS = $(check_PROGRAMS)
 
@@ -20,3 +21,6 @@
 
 ipmi_flashdata_unittest_SOURCES = ipmi_flashdata_unittest.cpp
 ipmi_flashdata_unittest_LDADD = $(top_builddir)/ipmi.o
+
+ipmi_validate_unittest_SOURCES = ipmi_validate_unittest.cpp
+ipmi_validate_unittest_LDADD = $(top_builddir)/ipmi.o
diff --git a/test/ipmi_flashdata_unittest.cpp b/test/ipmi_flashdata_unittest.cpp
index dcb27f6..9121d97 100644
--- a/test/ipmi_flashdata_unittest.cpp
+++ b/test/ipmi_flashdata_unittest.cpp
@@ -14,46 +14,6 @@
 // SoC.
 #define MAX_IPMI_BUFFER 64
 
-TEST(IpmiFlashData, InvalidRequestLengthReturnsFailure)
-{
-    // This request isn't large enough to be well-formed.
-
-    StrictMock<UpdaterMock> updater;
-
-    size_t dataLen;
-    uint8_t request[MAX_IPMI_BUFFER] = {0};
-    uint8_t reply[MAX_IPMI_BUFFER] = {0};
-
-    struct ChunkHdr tx;
-    tx.cmd = FlashSubCmds::flashDataBlock;
-    tx.offset = 0x00;
-    std::memcpy(request, &tx, sizeof(tx));
-
-    dataLen = sizeof(tx) - 1; // It's too small to be a valid packet.
-
-    EXPECT_EQ(IPMI_CC_INVALID, dataBlock(&updater, request, reply, &dataLen));
-}
-
-TEST(IpmiFlashData, NoDataReturnsFailure)
-{
-    // If the request has no data, it's invalid, returns failure.
-
-    StrictMock<UpdaterMock> updater;
-
-    size_t dataLen;
-    uint8_t request[MAX_IPMI_BUFFER] = {0};
-    uint8_t reply[MAX_IPMI_BUFFER] = {0};
-
-    struct ChunkHdr tx;
-    tx.cmd = FlashSubCmds::flashDataBlock;
-    tx.offset = 0x00;
-    std::memcpy(request, &tx, sizeof(tx));
-
-    dataLen = sizeof(tx); // It's only the header, so no data.
-
-    EXPECT_EQ(IPMI_CC_INVALID, dataBlock(&updater, request, reply, &dataLen));
-}
-
 TEST(IpmiFlashData, DataReceivedIsPassedOnOk)
 {
     // If valid data was passed in, it'll pass it onto the update handler.
diff --git a/test/ipmi_starttransfer_unittest.cpp b/test/ipmi_starttransfer_unittest.cpp
index 448287b..4bd9e35 100644
--- a/test/ipmi_starttransfer_unittest.cpp
+++ b/test/ipmi_starttransfer_unittest.cpp
@@ -15,27 +15,6 @@
 #define MAX_IPMI_BUFFER 64
 #define THIRTYTWO_MIB 33554432
 
-TEST(IpmiStartTransferTest, InvalidRequestLengthReturnsFailure)
-{
-    // Verify that the request is sanity checked w.r.t length.
-
-    StrictMock<UpdaterMock> updater;
-
-    size_t dataLen;
-    uint8_t request[MAX_IPMI_BUFFER] = {0};
-    uint8_t reply[MAX_IPMI_BUFFER] = {0};
-
-    struct StartTx tx;
-    tx.cmd = FlashSubCmds::flashStartTransfer;
-    tx.length = THIRTYTWO_MIB;
-    std::memcpy(request, &tx, sizeof(tx));
-
-    dataLen = sizeof(tx) - 1; // It's too small to be a valid packet.
-
-    EXPECT_EQ(IPMI_CC_INVALID,
-              startTransfer(&updater, request, reply, &dataLen));
-}
-
 TEST(IpmiStartTransferTest, ValidRequestBoringCase)
 {
     // Verify that if the request is valid it calls into the flash updater.
diff --git a/test/ipmi_validate_unittest.cpp b/test/ipmi_validate_unittest.cpp
new file mode 100644
index 0000000..ee600a0
--- /dev/null
+++ b/test/ipmi_validate_unittest.cpp
@@ -0,0 +1,39 @@
+#include "ipmi.hpp"
+
+#include <gtest/gtest.h>
+
+// ipmid.hpp isn't installed where we can grab it and this value is per BMC
+// SoC.
+#define MAX_IPMI_BUFFER 64
+
+TEST(IpmiValidateTest, BoringValidateCheckReturnsTrue)
+{
+    // Verify the validate check can return true when it's happy.
+    auto cmd = FlashSubCmds::flashStartTransfer;
+    size_t dataLen = sizeof(struct StartTx);
+    EXPECT_TRUE(validateRequestLength(cmd, dataLen));
+}
+
+TEST(IpmiValidateTest, InvalidLengthStartTransferReturnsFalse)
+{
+    // Verify that the request is sanity checked w.r.t length.
+    auto cmd = FlashSubCmds::flashStartTransfer;
+    size_t dataLen = sizeof(struct StartTx) - 1;
+    EXPECT_FALSE(validateRequestLength(cmd, dataLen));
+}
+
+TEST(IpmiValidateTest, InvalidLengthDataBlockReturnsFalse)
+{
+    // This request isn't large enough to be well-formed.
+    auto cmd = FlashSubCmds::flashDataBlock;
+    size_t dataLen = sizeof(struct ChunkHdr) - 1;
+    EXPECT_FALSE(validateRequestLength(cmd, dataLen));
+}
+
+TEST(IpmiValidateTest, DataBlockNoDataReturnsFalse)
+{
+    // If the request has no data, it's invalid, returns failure.
+    auto cmd = FlashSubCmds::flashDataBlock;
+    size_t dataLen = sizeof(struct ChunkHdr);
+    EXPECT_FALSE(validateRequestLength(cmd, dataLen));
+}