diff --git a/tests/scripts/generate_test_code.py b/tests/scripts/generate_test_code.py
index 9759f2a..6b5f11b 100755
--- a/tests/scripts/generate_test_code.py
+++ b/tests/scripts/generate_test_code.py
@@ -846,6 +846,14 @@
     return dep_check_code
 
 
+INT_VAL_REGEX = re.compile(r'-?(\d+|0x[0-9a-f]+)$', re.I)
+def val_is_int(val: str) -> bool:
+    """Whether val is suitable as an 'int' parameter in the .datax file."""
+    if not INT_VAL_REGEX.match(val):
+        return False
+    # Limit the range to what is guaranteed to get through strtol()
+    return abs(int(val, 0)) <= 0x7fffffff
+
 def write_parameters(out_data_f, test_args, func_args, unique_expressions):
     """
     Writes test parameters to the intermediate data file, replacing
@@ -864,9 +872,9 @@
         typ = func_args[i]
         val = test_args[i]
 
-        # check if val is a non literal int val (i.e. an expression)
-        if typ == 'int' and not re.match(r'(\d+|0x[0-9a-f]+)$',
-                                         val, re.I):
+        # Pass small integer constants literally. This reduces the size of
+        # the C code. Register anything else as an expression.
+        if typ == 'int' and not val_is_int(val):
             typ = 'exp'
             if val not in unique_expressions:
                 unique_expressions.append(val)
diff --git a/tests/suites/helpers.function b/tests/suites/helpers.function
index 1964731..7615d27 100644
--- a/tests/suites/helpers.function
+++ b/tests/suites/helpers.function
@@ -8,6 +8,8 @@
 #include <test/bignum_helpers.h>
 #include <test/psa_crypto_helpers.h>
 
+#include <errno.h>
+#include <limits.h>
 #include <stdint.h>
 #include <stdlib.h>
 #include <string.h>
diff --git a/tests/suites/host_test.function b/tests/suites/host_test.function
index a99a7c7..565ded3 100644
--- a/tests/suites/host_test.function
+++ b/tests/suites/host_test.function
@@ -32,46 +32,26 @@
  *
  * \return      0 if success else 1
  */
-int verify_int(char *str, int32_t *value)
+int verify_int(char *str, int32_t *p_value)
 {
-    size_t i;
-    int minus = 0;
-    int digits = 1;
-    int hex = 0;
-
-    for (i = 0; i < strlen(str); i++) {
-        if (i == 0 && str[i] == '-') {
-            minus = 1;
-            continue;
-        }
-
-        if (((minus && i == 2) || (!minus && i == 1)) &&
-            str[i - 1] == '0' && (str[i] == 'x' || str[i] == 'X')) {
-            hex = 1;
-            continue;
-        }
-
-        if (!((str[i] >= '0' && str[i] <= '9') ||
-              (hex && ((str[i] >= 'a' && str[i] <= 'f') ||
-                       (str[i] >= 'A' && str[i] <= 'F'))))) {
-            digits = 0;
-            break;
-        }
+    char *end = NULL;
+    errno = 0;
+    long value = strtol(str, &end, 0);
+    if (errno == EINVAL || *end != '\0') {
+        mbedtls_fprintf(stderr,
+                        "Expected integer for parameter and got: %s\n", str);
+        return KEY_VALUE_MAPPING_NOT_FOUND;
     }
-
-    if (digits) {
-        if (hex) {
-            *value = strtol(str, NULL, 16);
-        } else {
-            *value = strtol(str, NULL, 10);
-        }
-
-        return 0;
+    if (errno == ERANGE
+#if LONG_MAX > 0x7fffffff
+        || value > 0x7fffffffL || value < -0x80000000L
+#endif
+        ) {
+        mbedtls_fprintf(stderr, "Integer out of range: %s\n", str);
+        return KEY_VALUE_MAPPING_NOT_FOUND;
     }
-
-    mbedtls_fprintf(stderr,
-                    "Expected integer for parameter and got: %s\n", str);
-    return KEY_VALUE_MAPPING_NOT_FOUND;
+    *p_value = value;
+    return 0;
 }