diff --git a/CMakeLists.txt b/CMakeLists.txt
index f49ffadf..6c53d776 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -305,11 +305,22 @@ if(COMPILER_MSVC)
 
   list(APPEND RELIB_FLAGS -D_SCL_SECURE_NO_WARNINGS -D_CRT_SECURE_NO_WARNINGS -DWIN32_LEAN_AND_MEAN -DNOMINMAX /GR- /W3 /WX /wd4100 /wd4127 /wd4505 /wd4512 /wd4800 /wd4351)
 elseif(COMPILER_GCC OR COMPILER_CLANG)
-  list(APPEND RELIB_FLAGS -fms-extensions -Wall -Wextra -Werror -Wno-unused-function -Wno-unused-parameter -Wno-unused-variable -Wno-strict-aliasing -D_GNU_SOURCE)
+  list(APPEND RELIB_FLAGS
+    # used for unnamed structure fields
+    -fms-extensions
+    # enable most errors
+    -Wall -Wextra -Werror
+    # lax some of these common development warnings
+    -Wno-unused-function -Wno-unused-parameter -Wno-unused-variable -Wno-strict-aliasing
+    -D_GNU_SOURCE)
 
   if(COMPILER_GCC)
     list(APPEND RELIB_DEFS COMPILER_GCC=1)
 
+    # -format-truncation is too aggressive with snprintfs that are purposefully supposed
+    # to truncate on overflow
+    list(APPEND RELIB_FLAGS -Wno-format-truncation)
+
     # some flavors of gcc require this to be defined for the PR* macros in inttypes.h
     list(APPEND RELIB_FLAGS -D__STDC_FORMAT_MACROS)
   elseif(COMPILER_CLANG)
diff --git a/src/guest/arm7/arm7.c b/src/guest/arm7/arm7.c
index 5f2d742b..515f7bab 100644
--- a/src/guest/arm7/arm7.c
+++ b/src/guest/arm7/arm7.c
@@ -181,9 +181,6 @@ void arm7_suspend(struct arm7 *arm) {
 
 static void arm7_run(struct device *dev, int64_t ns) {
   struct arm7 *arm = (struct arm7 *)dev;
-  struct armv3_context *ctx = &arm->ctx;
-  struct jit *jit = arm->jit;
-
   static int64_t ARM7_CLOCK_FREQ = INT64_C(20000000);
   int cycles = (int)NANO_TO_CYCLES(ns, ARM7_CLOCK_FREQ);
 
@@ -232,7 +229,6 @@ static struct jit_guest *arm7_guest_create(struct arm7 *arm) {
 
 static int arm7_init(struct device *dev) {
   struct arm7 *arm = (struct arm7 *)dev;
-  struct dreamcast *dc = arm->dc;
 
   /* initialize jit */
   arm->guest = arm7_guest_create(arm);
diff --git a/src/guest/bios/bios.c b/src/guest/bios/bios.c
index a3c13c10..17f42f0e 100644
--- a/src/guest/bios/bios.c
+++ b/src/guest/bios/bios.c
@@ -67,7 +67,6 @@ static uint32_t bios_local_time() {
 static void bios_override_settings(struct bios *bios) {
   struct dreamcast *dc = bios->dc;
   struct flash *flash = dc->flash;
-  struct gdrom *gd = dc->gdrom;
 
   int region = 0;
   int lang = 0;
diff --git a/src/guest/bios/syscalls.c b/src/guest/bios/syscalls.c
index 00ef1690..02db5705 100644
--- a/src/guest/bios/syscalls.c
+++ b/src/guest/bios/syscalls.c
@@ -92,9 +92,6 @@ enum {
 static uint32_t bios_gdrom_send_cmd(struct bios *bios, uint32_t cmd_code,
                                     uint32_t params) {
   struct dreamcast *dc = bios->dc;
-  struct gdrom *gd = dc->gdrom;
-  struct holly *hl = dc->holly;
-  struct sh4 *sh4 = dc->sh4;
 
   if (bios->status != GDC_STATUS_NONE) {
     return 0;
@@ -123,8 +120,6 @@ static uint32_t bios_gdrom_send_cmd(struct bios *bios, uint32_t cmd_code,
 static void bios_gdrom_mainloop(struct bios *bios) {
   struct dreamcast *dc = bios->dc;
   struct gdrom *gd = dc->gdrom;
-  struct holly *hl = dc->holly;
-  struct sh4_context *ctx = &dc->sh4->ctx;
 
   if (bios->status != GDC_STATUS_ACTIVE) {
     return;
diff --git a/src/guest/gdrom/gdrom.c b/src/guest/gdrom/gdrom.c
index e6326445..98808e5b 100644
--- a/src/guest/gdrom/gdrom.c
+++ b/src/guest/gdrom/gdrom.c
@@ -429,7 +429,7 @@ static void gdrom_spi_cmd(struct gdrom *gd, int arg) {
       out[4] = (ses.fad & 0x0000ff00) >> 8;
       out[5] = (ses.fad & 0x000000ff);
 
-      gdrom_spi_write(gd, out, sizeof(out));
+      gdrom_spi_write(gd, out, size);
     } break;
 
     case GD_SPI_GET_SCD: {
diff --git a/src/guest/maple/maple.c b/src/guest/maple/maple.c
index 522c74bf..8d2109d6 100644
--- a/src/guest/maple/maple.c
+++ b/src/guest/maple/maple.c
@@ -24,8 +24,6 @@ static void maple_unregister_dev(struct maple *mp, int port, int unit) {
 
 static void maple_register_dev(struct maple *mp, const char *device_type,
                                int port, int unit) {
-  struct dreamcast *dc = mp->dc;
-
   CHECK(!mp->devs[port][unit],
         "maple_register_dev already registered for port=%d unit=%d", port,
         unit);
diff --git a/src/guest/pvr/ta.c b/src/guest/pvr/ta.c
index a2a56cce..9744284f 100644
--- a/src/guest/pvr/ta.c
+++ b/src/guest/pvr/ta.c
@@ -751,7 +751,6 @@ void ta_texture_write(struct ta *ta, uint32_t dst, const uint8_t *src,
 
 void ta_yuv_write(struct ta *ta, uint32_t dst, const uint8_t *src, int size) {
   struct holly *hl = ta->dc->holly;
-  struct pvr *pvr = ta->dc->pvr;
 
   CHECK(*hl->SB_LMMODE0 == 0);
   CHECK(size % ta->yuv_macroblock_size == 0);
diff --git a/src/guest/sh4/sh4.c b/src/guest/sh4/sh4.c
index 53ff8921..17625dc9 100644
--- a/src/guest/sh4/sh4.c
+++ b/src/guest/sh4/sh4.c
@@ -50,6 +50,8 @@ static void sh4_sr_updated(struct sh4 *sh4, uint32_t old_sr) {
 static void sh4_fpscr_updated(struct sh4 *sh4, uint32_t old_fpscr) {
   struct sh4_context *ctx = &sh4->ctx;
 
+  CHECK(!(ctx->fpscr & ENABLE_MASK), "FPU exceptions aren't supported");
+
   if ((ctx->fpscr & FR_MASK) != (old_fpscr & FR_MASK)) {
     sh4_swap_fpr_bank(ctx);
   }