diff --git a/Makefile b/Makefile
index abe5b0656..085e95fbc 100644
--- a/Makefile
+++ b/Makefile
@@ -222,13 +222,13 @@ showconfig:
 %.o: %.c *.h
 	$(CC) $(ALL_CCFLAGS) -c $< -o $@
 
-dump1090: dump1090.o anet.o interactive.o mode_ac.o mode_s.o comm_b.o net_io.o crc.o demod_2400.o stats.o cpr.o icao_filter.o track.o util.o convert.o ais_charset.o adaptive.o $(SDR_OBJ) $(COMPAT) $(CPUFEATURES_OBJS) $(STARCH_OBJS)
+dump1090: dump1090.o anet.o interactive.o mode_ac.o mode_s.o comm_b.o net_io.o crc.o demod_2400.o stats.o cpr.o icao_filter.o track.o util.o convert.o adaptive.o $(SDR_OBJ) $(COMPAT) $(CPUFEATURES_OBJS) $(STARCH_OBJS)
 	$(CC) -g -o $@ $^ $(LDFLAGS) $(LIBS) $(LIBS_SDR) $(LIBS_CURSES)
 
-view1090: view1090.o anet.o interactive.o mode_ac.o mode_s.o comm_b.o net_io.o crc.o stats.o cpr.o icao_filter.o track.o util.o ais_charset.o sdr_stub.o $(COMPAT)
+view1090: view1090.o anet.o interactive.o mode_ac.o mode_s.o comm_b.o net_io.o crc.o stats.o cpr.o icao_filter.o track.o util.o sdr_stub.o $(COMPAT)
 	$(CC) -g -o $@ $^ $(LDFLAGS) $(LIBS) $(LIBS_CURSES)
 
-faup1090: faup1090.o anet.o mode_ac.o mode_s.o comm_b.o net_io.o crc.o stats.o cpr.o icao_filter.o track.o util.o ais_charset.o sdr_stub.o $(COMPAT)
+faup1090: faup1090.o anet.o mode_ac.o mode_s.o comm_b.o net_io.o crc.o stats.o cpr.o icao_filter.o track.o util.o sdr_stub.o $(COMPAT)
 	$(CC) -g -o $@ $^ $(LDFLAGS) $(LIBS)
 
 starch-benchmark: cpu.o dsp/helpers/tables.o $(CPUFEATURES_OBJS) $(STARCH_OBJS) $(STARCH_BENCHMARK_OBJ)
@@ -252,7 +252,7 @@ benchmarks: oneoff/convert_benchmark
 oneoff/convert_benchmark: oneoff/convert_benchmark.o convert.o util.o dsp/helpers/tables.o cpu.o $(CPUFEATURES_OBJS) $(STARCH_OBJS)
 	$(CC) $(ALL_CCFLAGS) -g -o $@ $^ -lm -lpthread
 
-oneoff/decode_comm_b: oneoff/decode_comm_b.o comm_b.o ais_charset.o
+oneoff/decode_comm_b: oneoff/decode_comm_b.o comm_b.o
 	$(CC) $(ALL_CCFLAGS) -g -o $@ $^ -lm
 
 oneoff/dsp_error_measurement: oneoff/dsp_error_measurement.o dsp/helpers/tables.o cpu.o $(CPUFEATURES_OBJS) $(STARCH_OBJS)
diff --git a/ais_charset.c b/ais_charset.c
deleted file mode 100644
index a487e3cc7..000000000
--- a/ais_charset.c
+++ /dev/null
@@ -1,3 +0,0 @@
-#include "ais_charset.h"
-
-char ais_charset[64] = "@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_ !\"#$%&'()*+,-./0123456789:;<=>?";
diff --git a/ais_charset.h b/ais_charset.h
index 93d4a7293..40a9894f1 100644
--- a/ais_charset.h
+++ b/ais_charset.h
@@ -1,6 +1,10 @@
 #ifndef AIS_CHARSET_H
 #define AIS_CHARSET_H
 
-extern char ais_charset[64];
+// AIS character set is just the first 64 printable ASCII characters,
+// but with 0x20..0x3F after 0x40..0x5F.
+static inline __attribute__((always_inline)) char ais_to_ascii(unsigned i) {
+  return (i + 0x20) ^ 0b01100000;
+}
 
 #endif
diff --git a/comm_b.c b/comm_b.c
index a9b08fb2f..263c5e2c3 100644
--- a/comm_b.c
+++ b/comm_b.c
@@ -244,14 +244,14 @@ static int decodeBDS20(struct modesMessage *mm, bool store)
         return 0;
     }
 
-    callsign[0] = ais_charset[getbits(msg, 9, 14)];
-    callsign[1] = ais_charset[getbits(msg, 15, 20)];
-    callsign[2] = ais_charset[getbits(msg, 21, 26)];
-    callsign[3] = ais_charset[getbits(msg, 27, 32)];
-    callsign[4] = ais_charset[getbits(msg, 33, 38)];
-    callsign[5] = ais_charset[getbits(msg, 39, 44)];
-    callsign[6] = ais_charset[getbits(msg, 45, 50)];
-    callsign[7] = ais_charset[getbits(msg, 51, 56)];
+    callsign[0] = ais_to_ascii(getbits(msg, 9, 14));
+    callsign[1] = ais_to_ascii(getbits(msg, 15, 20));
+    callsign[2] = ais_to_ascii(getbits(msg, 21, 26));
+    callsign[3] = ais_to_ascii(getbits(msg, 27, 32));
+    callsign[4] = ais_to_ascii(getbits(msg, 33, 38));
+    callsign[5] = ais_to_ascii(getbits(msg, 39, 44));
+    callsign[6] = ais_to_ascii(getbits(msg, 45, 50));
+    callsign[7] = ais_to_ascii(getbits(msg, 51, 56));
     callsign[8] = 0;
 
     // score based on number of valid characters
diff --git a/interactive.c b/interactive.c
index 8761c955d..f56146d52 100644
--- a/interactive.c
+++ b/interactive.c
@@ -140,7 +140,7 @@ void interactiveShowData(void) {
     static bool need_clear = true;
     uint64_t now = mstime();
     char progress;
-    char spinner[4] = "|/-\\";
+    char spinner[4] = { '|', '/', '-', '\\' };
     int valid = 0;
     double signalMax = -100.0;
     double signalMin = +100.0;
diff --git a/mode_s.c b/mode_s.c
index adfb112a7..f1e5c84e8 100644
--- a/mode_s.c
+++ b/mode_s.c
@@ -802,14 +802,14 @@ static void decodeESIdentAndCategory(struct modesMessage *mm)
 
     mm->mesub = getbits(me, 6, 8);
 
-    mm->callsign[0] = ais_charset[getbits(me, 9, 14)];
-    mm->callsign[1] = ais_charset[getbits(me, 15, 20)];
-    mm->callsign[2] = ais_charset[getbits(me, 21, 26)];
-    mm->callsign[3] = ais_charset[getbits(me, 27, 32)];
-    mm->callsign[4] = ais_charset[getbits(me, 33, 38)];
-    mm->callsign[5] = ais_charset[getbits(me, 39, 44)];
-    mm->callsign[6] = ais_charset[getbits(me, 45, 50)];
-    mm->callsign[7] = ais_charset[getbits(me, 51, 56)];
+    mm->callsign[0] = ais_to_ascii(getbits(me, 9, 14));
+    mm->callsign[1] = ais_to_ascii(getbits(me, 15, 20));
+    mm->callsign[2] = ais_to_ascii(getbits(me, 21, 26));
+    mm->callsign[3] = ais_to_ascii(getbits(me, 27, 32));
+    mm->callsign[4] = ais_to_ascii(getbits(me, 33, 38));
+    mm->callsign[5] = ais_to_ascii(getbits(me, 39, 44));
+    mm->callsign[6] = ais_to_ascii(getbits(me, 45, 50));
+    mm->callsign[7] = ais_to_ascii(getbits(me, 51, 56));
     mm->callsign[8] = 0;
     mm->callsign_valid = 1;