diff --git a/src/sp_config.c b/src/sp_config.c
index 2d2631a5..de58c2a0 100644
--- a/src/sp_config.c
+++ b/src/sp_config.c
@@ -90,7 +90,7 @@ zend_result sp_process_rule(sp_parsed_keyword *parsed_rule, const sp_config_keyw
 
     if (!found_kw) {
       zend_string *kwname = zend_string_init(kw->kw, kw->kwlen, 0);
-      sp_log_err("config", "Unexpected keyword '%s' on line %d", ZSTR_VAL(kwname), kw->lineno);
+      sp_log_err("config", "Unexpected keyword '%s' on line %zu", ZSTR_VAL(kwname), kw->lineno);
       zend_string_release_ex(kwname, 0);
       return FAILURE;
     }
diff --git a/src/sp_config_scanner.h b/src/sp_config_scanner.h
index 560ea6e3..dda3dc26 100644
--- a/src/sp_config_scanner.h
+++ b/src/sp_config_scanner.h
@@ -15,7 +15,7 @@ typedef struct {
   const char *arg; // optional argument / can be not null terminated
   size_t arglen;
   sp_argtype argtype;
-  long lineno;
+  size_t lineno;
 } sp_parsed_keyword;
 
 zend_result sp_config_scan(const char *data, zend_result (*process_rule)(sp_parsed_keyword*));
diff --git a/src/sp_config_scanner.re b/src/sp_config_scanner.re
index 8f0b24eb..f9a6ce9b 100644
--- a/src/sp_config_scanner.re
+++ b/src/sp_config_scanner.re
@@ -90,11 +90,11 @@ static void str_dtor(zval *zv) {
 
 // sy_ functions and macros are helpers for the shunting yard algorithm
 #define sy_res_push(val) \
-  if (cond_res_i >= MAX_CONDITIONS) { cs_log_error("condition too complex on line %d", lineno); goto out; } \
+  if (cond_res_i >= MAX_CONDITIONS) { cs_log_error("condition too complex on line %zu", lineno); goto out; } \
   cond_res[cond_res_i++] = val;
 #define sy_res_pop() cond_res[--cond_res_i]
 #define sy_op_push(op) \
-  if (cond_op_i >= MAX_CONDITIONS) { cs_log_error("condition too complex on line %d", lineno); goto out; } \
+  if (cond_op_i >= MAX_CONDITIONS) { cs_log_error("condition too complex on line %zu", lineno); goto out; } \
   cond_op[cond_op_i++] = op;
 #define sy_op_pop() cond_op[--cond_op_i]
 #define sy_op_peek() cond_op[cond_op_i-1]
@@ -138,7 +138,7 @@ static int sy_apply_op(const char op, const int a, const int b) {
 #define SY_APPLY_OP_FROM_STACK() \
   char op = sy_op_pop(); \
   int unary = (op == '!'); \
-  if (cond_res_i < (2 - unary)) { cs_log_error("not enough input on line %d", lineno); goto out; } \
+  if (cond_res_i < (2 - unary)) { cs_log_error("not enough input on line %zu", lineno); goto out; } \
   int a = sy_res_pop(); \
   int b = unary ? 0 : sy_res_pop(); \
   int res = sy_apply_op(op, a, b); \
@@ -169,7 +169,7 @@ zend_result sp_config_scan(const char *data, zend_result (*process_rule)(sp_pars
   int cond_op_i = 0;
 
   int cond = yycinit;
-  long lineno = 1;
+  size_t lineno = 1;
 
   /*!stags:re2c format = 'const char *@@;\n'; */
   /*!re2c
@@ -189,7 +189,7 @@ zend_result sp_config_scan(const char *data, zend_result (*process_rule)(sp_pars
     keyword = [a-zA-Z][a-zA-Z0-9_]*;
     string = ["] ("\\"["] | [^"\r\n\x00])* ["];
 
-    <init> *                 { cs_log_error("parser error on line %d", lineno); goto out; }
+    <init> *                 { cs_log_error("parser error on line %zu", lineno); goto out; }
     <init> whitespace+       { goto yyc_init; }
     <init> [;#] [^\r\n\x00]* { goto yyc_init; }
     <init> newline           { lineno++; goto yyc_init; }
@@ -212,19 +212,19 @@ zend_result sp_config_scan(const char *data, zend_result (*process_rule)(sp_pars
     <init> ( "@log" | "@info" ) whitespace+ @t1 string @t2 ";" {
       if (!cond_res[0]) { goto yyc_init; }
       TMPSTR(tmpstr, t2, t1);
-      cs_log_info("[line %d]: %s", lineno, tmpstr);
+      cs_log_info("[line %zu]: %s", lineno, tmpstr);
       goto yyc_init;
     }
     <init> ( "@warn" | "@warning" ) whitespace+ @t1 string @t2 ";" {
       if (!cond_res[0]) { goto yyc_init; }
       TMPSTR(tmpstr, t2, t1);
-      cs_log_warning("[line %d]: %s", lineno, tmpstr);
+      cs_log_warning("[line %zu]: %s", lineno, tmpstr);
       goto yyc_init;
     }
     <init> ( "@err" | "@error" ) whitespace+ @t1 string @t2 ";" {
       if (!cond_res[0]) { goto yyc_init; }
       TMPSTR(tmpstr, t2, t1);
-      cs_log_error("[line %d]: %s", lineno, tmpstr);
+      cs_log_error("[line %zu]: %s", lineno, tmpstr);
       goto out;
     }
 
@@ -236,7 +236,7 @@ zend_result sp_config_scan(const char *data, zend_result (*process_rule)(sp_pars
         int is_loaded = (zend_hash_str_find_ptr(&module_registry, t3+1, t4-t3-2) != NULL);
         sy_res_push(is_loaded);
       } else {
-        cs_log_error("unknown function in condition on line %d", lineno);
+        cs_log_error("unknown function in condition on line %zu", lineno);
         goto out;
       }
       goto yyc_cond_op;
@@ -244,7 +244,7 @@ zend_result sp_config_scan(const char *data, zend_result (*process_rule)(sp_pars
     <cond> @t1 keyword @t2 {
       zend_string *tmp = zend_hash_str_find_ptr(&vars, t1, t2-t1);
       if (!tmp) {
-        cs_log_error("unknown variable in condition on line %d", lineno);
+        cs_log_error("unknown variable in condition on line %zu", lineno);
         goto out;
       }
       sy_res_push(atoi(ZSTR_VAL(tmp)));
@@ -280,27 +280,27 @@ zend_result sp_config_scan(const char *data, zend_result (*process_rule)(sp_pars
         SY_APPLY_OP_FROM_STACK();
       }
       if (cond_op_i == 0 || sy_op_peek() != '(') {
-        cs_log_error("unbalanced parenthesis on line %d", lineno); goto out;
+        cs_log_error("unbalanced parenthesis on line %zu", lineno); goto out;
       }
       cond_op_i--;
       goto yyc_cond_op;
     }
     <cond_op> ";" {
       while (cond_op_i) {
-        if (sy_op_peek() == '(') { cs_log_error("unbalanced parenthesis on line %d", lineno); goto out; }
+        if (sy_op_peek() == '(') { cs_log_error("unbalanced parenthesis on line %zu", lineno); goto out; }
         SY_APPLY_OP_FROM_STACK();
       }
-      if (cond_res_i > 1) { cs_log_error("invalid condition on line %d", lineno); goto out; }
+      if (cond_res_i > 1) { cs_log_error("invalid condition on line %zu", lineno); goto out; }
       goto yyc_init;
     }
-    <cond, cond_op> * { cs_log_error("syntax error in condition on line %d", lineno); goto out; }
+    <cond, cond_op> * { cs_log_error("syntax error in condition on line %zu", lineno); goto out; }
 
     <rule> whitespace+     {  goto yyc_rule; }
     <rule> newline / ( newline | whitespace )* "." {  lineno++; goto yyc_rule; }
     <rule> "." @t1 keyword @t2 ( "(" @t3 ( string? | keyword ) @t4 ")" )? {
       if (!cond_res[0]) { goto yyc_rule; }
       if (kw_i == MAX_KEYWORDS) {
-        cs_log_error("too many keywords in rule (more than %d) on line %d", MAX_KEYWORDS, lineno);
+        cs_log_error("too many keywords in rule (more than %d) on line %zu", MAX_KEYWORDS, lineno);
         goto out;
       }
       sp_parsed_keyword kw = {
@@ -321,7 +321,7 @@ zend_result sp_config_scan(const char *data, zend_result (*process_rule)(sp_pars
         } else {
           zend_string *tmp = zend_hash_str_find_ptr(&vars, t3, t4-t3);
           if (!tmp) {
-            cs_log_error("unknown variable on line %d", lineno);
+            cs_log_error("unknown variable on line %zu", lineno);
             goto out;
           }
           kw.arg = ZSTR_VAL(tmp);
diff --git a/src/sp_ini.c b/src/sp_ini.c
index 8860a929..cfbc615b 100644
--- a/src/sp_ini.c
+++ b/src/sp_ini.c
@@ -97,7 +97,7 @@ static bool /* success */ sp_ini_check(zend_string *const restrict varname, zend
       if (entry->msg) {
         sp_log_ini_check_violation("%s", ZSTR_VAL(entry->msg));
       } else {
-        sp_log_ini_check_violation("INI value %lld for `%s` out of range", lvalue, ZSTR_VAL(entry->key));
+        sp_log_ini_check_violation("INI value " ZEND_LONG_FMT " for `%s` out of range", lvalue, ZSTR_VAL(entry->key));
       }
       return simulation;
     }
diff --git a/src/sp_utils.h b/src/sp_utils.h
index 36caa524..1146db3b 100644
--- a/src/sp_utils.h
+++ b/src/sp_utils.h
@@ -71,6 +71,11 @@ extern int sp_debug_stderr;
 #define GET_SUFFIX(x) (x == 1) ? "st" : ((x == 2) ? "nd" : "th")
 
 const char *get_ipaddr(void);
+#if defined __has_attribute
+#  if __has_attribute (__format__)
+     __attribute__((__format__(printf, 4, 5)))
+#  endif
+#endif
 void sp_log_msgf(char const* const restrict feature, int level, int type, char const* const restrict fmt, ...);
 int compute_hash(char const* const restrict filename, char *restrict file_hash);
 const zend_string *sp_zval_to_zend_string(const zval *);