diff --git a/semver/patterns.py b/semver/patterns.py
index 63cce54..75944f4 100644
--- a/semver/patterns.py
+++ b/semver/patterns.py
@@ -11,12 +11,12 @@
     MODIFIERS
 )
 
-COMPLETE_VERSION = re.compile("(?i)" + _COMPLETE_VERSION)
+COMPLETE_VERSION = re.compile("(?i)" + _COMPLETE_VERSION + "$")
 
 CARET_CONSTRAINT = re.compile(r"(?i)^\^({})$".format(_COMPLETE_VERSION))
 TILDE_CONSTRAINT = re.compile("(?i)^~(?!=)({})$".format(_COMPLETE_VERSION))
 TILDE_PEP440_CONSTRAINT = re.compile("(?i)^~=({})$".format(_COMPLETE_VERSION))
 X_CONSTRAINT = re.compile(r"^(!=|==)?\s*v?(\d+)(?:\.(\d+))?(?:\.(\d+))?(?:\.[xX*])+$")
 BASIC_CONSTRAINT = re.compile(
-    r"(?i)^(<>|!=|>=?|<=?|==?)?\s*({}|dev)".format(_COMPLETE_VERSION)
+    r"(?i)^(<>|!=|>=?|<=?|==?)?\s*({}|dev)$".format(_COMPLETE_VERSION)
 )