diff --git a/src/FTL.h b/src/FTL.h
index 1443b62e0..0d1280a15 100644
--- a/src/FTL.h
+++ b/src/FTL.h
@@ -59,11 +59,11 @@
 #define MAXITER 1000
 
 // How many hours do we want to store in FTL's memory? [hours]
-#define MAXLOGAGE 24
+#define MAXLOGAGE 24u
 
 // Interval for overTime data [seconds]
 // Default: 600 (10 minutes)
-#define OVERTIME_INTERVAL 600
+#define OVERTIME_INTERVAL 600u
 
 // How many overTime slots do we need?
 // This is the maximum log age divided by the overtime interval
diff --git a/src/database/aliasclients.c b/src/database/aliasclients.c
index cf9180fdc..4a2010a63 100644
--- a/src/database/aliasclients.c
+++ b/src/database/aliasclients.c
@@ -84,7 +84,7 @@ static void recompute_aliasclient(const int aliasclientID)
 		// Add counts of this client to the alias-client
 		aliasclient->count += client->count;
 		aliasclient->blockedcount += client->blockedcount;
-		for(int idx = 0; idx < OVERTIME_SLOTS; idx++)
+		for(unsigned int idx = 0; idx < OVERTIME_SLOTS; idx++)
 			aliasclient->overTime[idx] += client->overTime[idx];
 	}
 }
diff --git a/src/datastructure.c b/src/datastructure.c
index 6db83f69c..1c8fc2a7f 100644
--- a/src/datastructure.c
+++ b/src/datastructure.c
@@ -414,7 +414,7 @@ void change_clientcount(clientsData *client, int total, int blocked, int overTim
 {
 		client->count += total;
 		client->blockedcount += blocked;
-		if(overTimeIdx > -1 && overTimeIdx < OVERTIME_SLOTS)
+		if(overTimeIdx > -1 && (unsigned int)overTimeIdx < OVERTIME_SLOTS)
 		{
 			overTime[overTimeIdx].total += overTimeMod;
 			client->overTime[overTimeIdx] += overTimeMod;
@@ -432,7 +432,7 @@ void change_clientcount(clientsData *client, int total, int blocked, int overTim
 			clientsData *aliasclient = getClient(client->aliasclient_id, true);
 			aliasclient->count += total;
 			aliasclient->blockedcount += blocked;
-			if(overTimeIdx > -1 && overTimeIdx < OVERTIME_SLOTS)
+			if(overTimeIdx > -1 && (unsigned int)overTimeIdx < OVERTIME_SLOTS)
 				aliasclient->overTime[overTimeIdx] += overTimeMod;
 		}
 }
diff --git a/src/gc.c b/src/gc.c
index 2235a722b..dfc9192a9 100644
--- a/src/gc.c
+++ b/src/gc.c
@@ -263,7 +263,7 @@ static void recycle(void)
  *
  * @return The maximum overtime slot as an unsigned integer.
  */
-unsigned int get_max_overtime_slot(void)
+unsigned int __attribute__((pure)) get_max_overtime_slot(void)
 {
 	return min(config.webserver.api.maxHistory.v.ui, MAXLOGAGE * 3600) / OVERTIME_INTERVAL - 1;
 }
diff --git a/src/gc.h b/src/gc.h
index 48aa5045b..cb078a11d 100644
--- a/src/gc.h
+++ b/src/gc.h
@@ -15,7 +15,7 @@
 
 void *GC_thread(void *val);
 void runGC(const time_t now, time_t *lastGCrun, const bool flush);
-unsigned int get_max_overtime_slot(void);
+unsigned int get_max_overtime_slot(void) __attribute__((pure));
 int get_rate_limit_turnaround(const unsigned int rate_limit_count);
 unsigned int set_gc_interval(void);
 
diff --git a/src/overTime.c b/src/overTime.c
index 9dca275ba..5c327f492 100644
--- a/src/overTime.c
+++ b/src/overTime.c
@@ -85,12 +85,12 @@ void initOverTime(void)
 		localtime_r(&newest, &tm_n);
 		strftime(first, 20, "%Y-%m-%d %H:%M:%S", &tm_o);
 		strftime(last, 20, "%Y-%m-%d %H:%M:%S", &tm_n);
-		log_debug(DEBUG_OVERTIME, "initOverTime(): Initializing %i slots from %s (%lu) to %s (%lu)",
+		log_debug(DEBUG_OVERTIME, "initOverTime(): Initializing %u slots from %s (%lu) to %s (%lu)",
 		          OVERTIME_SLOTS, first, (unsigned long)oldest, last, (unsigned long)newest);
 	}
 
 	// Iterate over overTime
-	for(int i = 0; i < OVERTIME_SLOTS; i++)
+	for(unsigned int i = 0; i < OVERTIME_SLOTS; i++)
 	{
 		time_t this_slot_ts = oldest + OVERTIME_INTERVAL * i;
 		// Initialize overTime slot
@@ -117,14 +117,14 @@ unsigned int _getOverTimeID(time_t timestamp, const char *file, const int line)
 		// Return first timestamp in case negative timestamp was determined
 		return 0;
 	}
-	else if(id == OVERTIME_SLOTS)
+	else if((unsigned int)id == OVERTIME_SLOTS)
 	{
 		// Possible race-collision (moving of the timeslots is just about to
 		// happen), silently add to the last bin because this is the correct
 		// thing to do
 		return OVERTIME_SLOTS-1;
 	}
-	else if(id > OVERTIME_SLOTS)
+	else if((unsigned int)id > OVERTIME_SLOTS)
 	{
 		// This is definitely wrong. We warn about this (but only once)
 		if(!warned_about_hwclock)