diff --git a/include/haproxy/tools.h b/include/haproxy/tools.h
index 8e29d38cc..aa9fd777c 100644
--- a/include/haproxy/tools.h
+++ b/include/haproxy/tools.h
@@ -1256,6 +1256,23 @@ static inline void update_char_fingerprint(uint8_t *fp, char prev, char curr)
 	fp[32 * from + to]++;
 }
 
+/* checks that the numerical argument, if passed without units and is non-zero,
+ * is at least as large as value <min>. It returns 1 if the value is too small,
+ * otherwise zero. This is used to warn about the use of small values without
+ * units.
+ */
+static inline int warn_if_lower(const char *text, long min)
+{
+	int digits;
+	long value;
+
+	digits = strspn(text, "0123456789");
+	if (digits < strlen(text))
+		return 0; // there are non-digits here.
+
+	value = atol(text);
+	return value && value < min;
+}
 
 /* compare the current OpenSSL version to a string */
 int openssl_compare_current_version(const char *version);
diff --git a/src/check.c b/src/check.c
index 85691de87..29a86b7dd 100644
--- a/src/check.c
+++ b/src/check.c
@@ -2190,6 +2190,12 @@ static int srv_parse_agent_inter(char **args, int *cur_arg, struct proxy *curpx,
 	}
 	srv->agent.inter = delay;
 
+	if (warn_if_lower(args[*cur_arg+1], 100)) {
+		memprintf(errmsg, "'%s %u' in server '%s' is suspiciously small for a value in milliseconds. Please use an explicit unit ('%ums') if that was the intent",
+		          args[*cur_arg], delay, srv->id, delay);
+		err_code |= ERR_WARN;
+	}
+
   out:
 	return err_code;
 
@@ -2459,6 +2465,12 @@ static int srv_parse_check_inter(char **args, int *cur_arg, struct proxy *curpx,
 	}
 	srv->check.inter = delay;
 
+	if (warn_if_lower(args[*cur_arg+1], 100)) {
+		memprintf(errmsg, "'%s %u' in server '%s' is suspiciously small for a value in milliseconds. Please use an explicit unit ('%ums') if that was the intent",
+		          args[*cur_arg], delay, srv->id, delay);
+		err_code |= ERR_WARN;
+	}
+
   out:
 	return err_code;
 
@@ -2504,6 +2516,12 @@ static int srv_parse_check_fastinter(char **args, int *cur_arg, struct proxy *cu
 	}
 	srv->check.fastinter = delay;
 
+	if (warn_if_lower(args[*cur_arg+1], 100)) {
+		memprintf(errmsg, "'%s %u' in server '%s' is suspiciously small for a value in milliseconds. Please use an explicit unit ('%ums') if that was the intent",
+		          args[*cur_arg], delay, srv->id, delay);
+		err_code |= ERR_WARN;
+	}
+
   out:
 	return err_code;
 
@@ -2549,6 +2567,12 @@ static int srv_parse_check_downinter(char **args, int *cur_arg, struct proxy *cu
 	}
 	srv->check.downinter = delay;
 
+	if (warn_if_lower(args[*cur_arg+1], 100)) {
+		memprintf(errmsg, "'%s %u' in server '%s' is suspiciously small for a value in milliseconds. Please use an explicit unit ('%ums') if that was the intent",
+		          args[*cur_arg], delay, srv->id, delay);
+		err_code |= ERR_WARN;
+	}
+
   out:
 	return err_code;
 
diff --git a/src/proxy.c b/src/proxy.c
index 6f951cd50..357704209 100644
--- a/src/proxy.c
+++ b/src/proxy.c
@@ -620,6 +620,12 @@ static int proxy_parse_timeout(char **args, int section, struct proxy *proxy,
 		return -1;
 	}
 
+	if (warn_if_lower(args[1], 100)) {
+		memprintf(err, "'timeout %s %u' in %s '%s' is suspiciously small for a value in milliseconds. Please use an explicit unit ('%ums') if that was the intent.",
+		          name, timeout, proxy_type_str(proxy), proxy->id, timeout);
+		retval = 1;
+	}
+
 	if (!(proxy->cap & cap)) {
 		memprintf(err, "'timeout %s' will be ignored because %s '%s' has no %s capability",
 		          name, proxy_type_str(proxy), proxy->id,
diff --git a/src/resolvers.c b/src/resolvers.c
index 887468980..f8f0c8edf 100644
--- a/src/resolvers.c
+++ b/src/resolvers.c
@@ -3733,6 +3733,12 @@ int cfg_parse_resolvers(const char *file, int linenum, char **args, int kwm)
 			goto out;
 		}
 
+		if (warn_if_lower(args[2], 100)) {
+			ha_alert("parsing [%s:%d] : '%s %s %u' looks suspiciously small for a value in milliseconds."
+				 " Please use an explicit unit ('%ums') if that was the intent.\n",
+				 file, linenum, args[0], args[1], time, time);
+			err_code |= ERR_WARN;
+		}
 	}
 	else if (strcmp(args[0], "accepted_payload_size") == 0) {
 		int i = 0;
@@ -3813,6 +3819,12 @@ int cfg_parse_resolvers(const char *file, int linenum, char **args, int kwm)
 				curr_resolvers->px->timeout.connect = tout;
 			}
 
+			if (warn_if_lower(args[2], 100)) {
+				ha_alert("parsing [%s:%d] : '%s %s %u' looks suspiciously small for a value in milliseconds."
+					 " Please use an explicit unit ('%ums') if that was the intent.\n",
+					 file, linenum, args[0], args[1], tout, tout);
+				err_code |= ERR_WARN;
+			}
 		}
 		else {
 			ha_alert("parsing [%s:%d] : '%s' expects 'retry' or 'resolve' and <time> as arguments got '%s'.\n",