diff --git a/src/script/sigencoding.cpp b/src/script/sigencoding.cpp
--- a/src/script/sigencoding.cpp
+++ b/src/script/sigencoding.cpp
@@ -135,34 +135,28 @@
 }
 
 static bool IsCompressedOrUncompressedPubKey(const valtype &vchPubKey) {
-    if (vchPubKey.size() < 33) {
-        //  Non-canonical public key: too short
-        return false;
-    }
-    if (vchPubKey[0] == 0x04) {
-        if (vchPubKey.size() != 65) {
-            //  Non-canonical public key: invalid length for uncompressed key
-            return false;
-        }
-    } else if (vchPubKey[0] == 0x02 || vchPubKey[0] == 0x03) {
-        if (vchPubKey.size() != 33) {
-            //  Non-canonical public key: invalid length for compressed key
+    switch (vchPubKey.size()) {
+        case 33:
+            // Compressed public key: must start with 0x02 or 0x03.
+            return vchPubKey[0] == 0x02 || vchPubKey[0] == 0x03;
+
+        case 65:
+            // Non-compressed public key: must start with 0x04.
+            return vchPubKey[0] == 0x04;
+
+        default:
+            // Non-canonical public key: invalid size.
             return false;
-        }
-    } else {
-        //  Non-canonical public key: neither compressed nor uncompressed
-        return false;
     }
-    return true;
 }
 
 static bool IsCompressedPubKey(const valtype &vchPubKey) {
     if (vchPubKey.size() != 33) {
-        //  Non-canonical public key: invalid length for compressed key
+        // Non-canonical public key: invalid length for compressed key
         return false;
     }
     if (vchPubKey[0] != 0x02 && vchPubKey[0] != 0x03) {
-        //  Non-canonical public key: invalid prefix for compressed key
+        // Non-canonical public key: invalid prefix for compressed key
         return false;
     }
     return true;
@@ -170,7 +164,7 @@
 
 bool CheckPubKeyEncoding(const valtype &vchPubKey, uint32_t flags,
                          ScriptError *serror) {
-    if ((flags & SCRIPT_VERIFY_STRICTENC) != 0 &&
+    if ((flags & SCRIPT_VERIFY_STRICTENC) &&
         !IsCompressedOrUncompressedPubKey(vchPubKey)) {
         return set_error(serror, SCRIPT_ERR_PUBKEYTYPE);
     }
diff --git a/src/test/sigencoding_tests.cpp b/src/test/sigencoding_tests.cpp
--- a/src/test/sigencoding_tests.cpp
+++ b/src/test/sigencoding_tests.cpp
@@ -32,6 +32,11 @@
         // Degenerate keys.
         {},
         {0x00},
+        {0x01},
+        {0x02},
+        {0x03},
+        {0x04},
+        {0x05},
         {0x42},
         {0xff},
         // Invalid first byte 0x00.