diff --git a/include/cpputils/env_var.h b/include/cpputils/env_var.h
index 3427a31..b3a85c1 100644
--- a/include/cpputils/env_var.h
+++ b/include/cpputils/env_var.h
@@ -3,6 +3,7 @@
 #include <cstdlib>
 #include <cstring>
 #include <iostream>
+#include <limits>
 #include <string>
 #include <unordered_map>
 
@@ -70,31 +71,50 @@ class EnvVarRegistry {
   };                                                                      \
   }
 
-#define DEFINE_ENV_VAR_INT(TYPE, name, DEFAULT_VALUE)                     \
-  namespace EnvVars {                                                     \
-  struct name {                                                           \
-    static constexpr TYPE DEFAULT = DEFAULT_VALUE;                        \
-    static constexpr char const* NAME = #name;                            \
-    static TYPE GET() {                                                   \
-      auto c = std::getenv(#name);                                        \
-      if (c) {                                                            \
-        if (std::strlen(c) > 0) {                                         \
-          try {                                                           \
-            if constexpr (std::is_unsigned_v<TYPE>) {                     \
-              TYPE x = static_cast<TYPE>(std::stoull(c));                 \
-              return x;                                                   \
-            } else {                                                      \
-              TYPE x = static_cast<TYPE>(std::stoll(c));                  \
-              return x;                                                   \
-            }                                                             \
-          } catch (...) {}                                                \
-        }                                                                 \
-      }                                                                   \
-      return DEFAULT_VALUE;                                               \
-    }                                                                     \
-    static inline ::cpputils::env_var::EnvVarRegistry::EnvVarAutoRegister \
-        _env_register{#name, DEFAULT_VALUE};                              \
-  };                                                                      \
+#define DEFINE_ENV_VAR_INT(TYPE, name, DEFAULT_VALUE)                       \
+  namespace EnvVars {                                                       \
+  struct name {                                                             \
+    static constexpr TYPE DEFAULT = DEFAULT_VALUE;                          \
+    static constexpr char const* NAME = #name;                              \
+    static TYPE GET() {                                                     \
+      constexpr auto lower_bound = std::numeric_limits<TYPE>::min();        \
+      constexpr auto upper_bound = std::numeric_limits<TYPE>::max();        \
+      auto c = std::getenv(#name);                                          \
+      if (c) {                                                              \
+        if (std::strlen(c) > 0) {                                           \
+          try {                                                             \
+            if constexpr (std::is_unsigned_v<TYPE>) {                       \
+              const char* p = c;                                            \
+              while (*p == ' ' || *p == '\t' || *p == '\n' || *p == '\r') { \
+                ++p;                                                        \
+              }                                                             \
+              if (*p == '-') {                                              \
+                return lower_bound;                                         \
+              }                                                             \
+              auto x = std::stoull(c);                                      \
+              if (x > upper_bound) {                                        \
+                return upper_bound;                                         \
+              } else {                                                      \
+                return x;                                                   \
+              }                                                             \
+            } else {                                                        \
+              auto x = std::stoll(c);                                       \
+              if (x > upper_bound) {                                        \
+                return upper_bound;                                         \
+              } else if (x < lower_bound) {                                 \
+                return lower_bound;                                         \
+              } else {                                                      \
+                return x;                                                   \
+              }                                                             \
+            }                                                               \
+          } catch (...) {}                                                  \
+        }                                                                   \
+      }                                                                     \
+      return DEFAULT_VALUE;                                                 \
+    }                                                                       \
+    static inline ::cpputils::env_var::EnvVarRegistry::EnvVarAutoRegister   \
+        _env_register{#name, DEFAULT_VALUE};                                \
+  };                                                                        \
   }
 
 }  // namespace env_var