diff --git a/apps/shared/avifjpeg.c b/apps/shared/avifjpeg.c
index 6b00681628..d48beaaf80 100644
--- a/apps/shared/avifjpeg.c
+++ b/apps/shared/avifjpeg.c
@@ -297,13 +297,13 @@ static uint32_t avifJPEGReadUint32LittleEndian(const uint8_t * src)
 // Reads a 2-byte unsigned integer in big-endian format from the raw bitstream src.
 static uint16_t avifJPEGReadUint16BigEndian(const uint8_t * src)
 {
-    return ((uint32_t)src[0] << 8) | ((uint32_t)src[1] << 0);
+    return (uint16_t)((src[0] << 8) | (src[1] << 0));
 }
 
 // Reads a 2-byte unsigned integer in little-endian format from the raw bitstream src.
 static uint16_t avifJPEGReadUint16LittleEndian(const uint8_t * src)
 {
-    return ((uint32_t)src[0] << 0) | ((uint32_t)src[1] << 8);
+    return (uint16_t)((src[0] << 0) | (src[1] << 8));
 }
 
 // Reads 'numBytes' at 'offset', stores them in 'bytes' and increases 'offset'.
diff --git a/apps/shared/y4m.c b/apps/shared/y4m.c
index bd9c287d3b..afdb59f1d7 100644
--- a/apps/shared/y4m.c
+++ b/apps/shared/y4m.c
@@ -138,7 +138,7 @@ static avifBool y4mColorSpaceParse(const char * formatString, struct y4mFrameIte
 
 // Returns an unsigned integer value parsed from [start:end[.
 // Returns -1 in case of failure.
-int y4mReadUnsignedInt(const char * start, const char * end)
+static int y4mReadUnsignedInt(const char * start, const char * end)
 {
     const char * p = start;
     int64_t value = 0;
diff --git a/include/avif/avif.h b/include/avif/avif.h
index ae8714e2be..6fd32f9f7d 100644
--- a/include/avif/avif.h
+++ b/include/avif/avif.h
@@ -701,7 +701,7 @@ typedef struct avifGainMap
 
 // Allocates a gain map. Returns NULL if a memory allocation failed.
 // The 'image' field is NULL by default and must be allocated separately.
-AVIF_API avifGainMap * avifGainMapCreate();
+AVIF_API avifGainMap * avifGainMapCreate(void);
 // Frees a gain map, including the 'image' field if non NULL.
 AVIF_API void avifGainMapDestroy(avifGainMap * gainMap);
 
diff --git a/include/avif/internal.h b/include/avif/internal.h
index b30304f6ef..d81e698b3b 100644
--- a/include/avif/internal.h
+++ b/include/avif/internal.h
@@ -558,19 +558,19 @@ struct avifCodecInternal;
 
 typedef enum avifEncoderChange
 {
-    AVIF_ENCODER_CHANGE_MIN_QUANTIZER = (1u << 0),
-    AVIF_ENCODER_CHANGE_MAX_QUANTIZER = (1u << 1),
-    AVIF_ENCODER_CHANGE_MIN_QUANTIZER_ALPHA = (1u << 2),
-    AVIF_ENCODER_CHANGE_MAX_QUANTIZER_ALPHA = (1u << 3),
-    AVIF_ENCODER_CHANGE_TILE_ROWS_LOG2 = (1u << 4),
-    AVIF_ENCODER_CHANGE_TILE_COLS_LOG2 = (1u << 5),
-    AVIF_ENCODER_CHANGE_QUANTIZER = (1u << 6),
-    AVIF_ENCODER_CHANGE_QUANTIZER_ALPHA = (1u << 7),
-    AVIF_ENCODER_CHANGE_SCALING_MODE = (1u << 8),
-
-    AVIF_ENCODER_CHANGE_CODEC_SPECIFIC = (1u << 31)
+    AVIF_ENCODER_CHANGE_MIN_QUANTIZER = (1 << 0),
+    AVIF_ENCODER_CHANGE_MAX_QUANTIZER = (1 << 1),
+    AVIF_ENCODER_CHANGE_MIN_QUANTIZER_ALPHA = (1 << 2),
+    AVIF_ENCODER_CHANGE_MAX_QUANTIZER_ALPHA = (1 << 3),
+    AVIF_ENCODER_CHANGE_TILE_ROWS_LOG2 = (1 << 4),
+    AVIF_ENCODER_CHANGE_TILE_COLS_LOG2 = (1 << 5),
+    AVIF_ENCODER_CHANGE_QUANTIZER = (1 << 6),
+    AVIF_ENCODER_CHANGE_QUANTIZER_ALPHA = (1 << 7),
+    AVIF_ENCODER_CHANGE_SCALING_MODE = (1 << 8),
+
+    AVIF_ENCODER_CHANGE_CODEC_SPECIFIC = (1 << 30)
 } avifEncoderChange;
-typedef uint32_t avifEncoderChanges;
+typedef int avifEncoderChanges;
 
 typedef avifBool (*avifCodecGetNextImageFunc)(struct avifCodec * codec,
                                               struct avifDecoder * decoder,
diff --git a/src/avif.c b/src/avif.c
index a220361a91..00dc4c8fab 100644
--- a/src/avif.c
+++ b/src/avif.c
@@ -1165,7 +1165,7 @@ void avifCodecVersions(char outBuffer[256])
 }
 
 #if defined(AVIF_ENABLE_EXPERIMENTAL_GAIN_MAP)
-avifGainMap * avifGainMapCreate()
+avifGainMap * avifGainMapCreate(void)
 {
     avifGainMap * gainMap = (avifGainMap *)avifAlloc(sizeof(avifGainMap));
     if (!gainMap) {
diff --git a/src/codec_aom.c b/src/codec_aom.c
index ae91307696..d11f8ee4e5 100644
--- a/src/codec_aom.c
+++ b/src/codec_aom.c
@@ -1099,7 +1099,7 @@ static avifResult aomCodecEncodeImage(avifCodec * codec,
             }
             // Set the U plane to 0.5.
             if (image->depth > 8) {
-                const uint16_t half = 1 << (image->depth - 1);
+                const uint16_t half = (uint16_t)(1 << (image->depth - 1));
                 for (uint32_t j = 0; j < monoUVHeight; ++j) {
                     uint16_t * dstRow = (uint16_t *)&aomImage.planes[1][(size_t)j * aomImage.stride[1]];
                     for (uint32_t i = 0; i < monoUVWidth; ++i) {
diff --git a/src/obu.c b/src/obu.c
index 0ef7dad545..6bba73baf5 100644
--- a/src/obu.c
+++ b/src/obu.c
@@ -328,6 +328,8 @@ static avifBool parseSequenceHeaderColorConfig(avifBits * bits, avifSequenceHead
                     header->yuvFormat = AVIF_PIXEL_FORMAT_YUV444;
                 }
                 break;
+            default:
+                return AVIF_FALSE;
         }
 
         if (subsampling_x && subsampling_y) {
diff --git a/src/read.c b/src/read.c
index b44108888b..a942841a61 100644
--- a/src/read.c
+++ b/src/read.c
@@ -278,7 +278,7 @@ typedef struct avifSampleTable
 
 static void avifSampleTableDestroy(avifSampleTable * sampleTable);
 
-static avifSampleTable * avifSampleTableCreate()
+static avifSampleTable * avifSampleTableCreate(void)
 {
     avifSampleTable * sampleTable = (avifSampleTable *)avifAlloc(sizeof(avifSampleTable));
     if (sampleTable == NULL) {
@@ -750,7 +750,7 @@ typedef struct avifMeta
 
 static void avifMetaDestroy(avifMeta * meta);
 
-static avifMeta * avifMetaCreate()
+static avifMeta * avifMetaCreate(void)
 {
     avifMeta * meta = (avifMeta *)avifAlloc(sizeof(avifMeta));
     if (meta == NULL) {
@@ -883,7 +883,7 @@ typedef struct avifDecoderData
 
 static void avifDecoderDataDestroy(avifDecoderData * data);
 
-static avifDecoderData * avifDecoderDataCreate()
+static avifDecoderData * avifDecoderDataCreate(void)
 {
     avifDecoderData * data = (avifDecoderData *)avifAlloc(sizeof(avifDecoderData));
     if (data == NULL) {
@@ -5351,7 +5351,7 @@ avifResult avifDecoderReset(avifDecoder * decoder)
                 if (!foundItem) {
                     AVIF_CHECKERR(numExtraInputImageItems < AVIF_SAMPLE_TRANSFORM_MAX_NUM_EXTRA_INPUT_IMAGE_ITEMS,
                                   AVIF_RESULT_NOT_IMPLEMENTED);
-                    *category = AVIF_ITEM_SAMPLE_TRANSFORM_INPUT_0_COLOR + numExtraInputImageItems;
+                    *category = (avifItemCategory)(AVIF_ITEM_SAMPLE_TRANSFORM_INPUT_0_COLOR + numExtraInputImageItems);
                     alphaCategory = AVIF_ITEM_SAMPLE_TRANSFORM_INPUT_0_ALPHA + numExtraInputImageItems;
                     mainItems[*category] = inputImageItem;
                     ++numExtraInputImageItems;
@@ -5441,7 +5441,7 @@ avifResult avifDecoderReset(avifDecoder * decoder)
             if (avifIsAlpha((avifItemCategory)c) && !isAlphaItemInInput) {
                 // In this case, the made up grid item will not have an associated pixi property. So validate everything else
                 // but the pixi property.
-                strictFlags &= ~AVIF_STRICT_PIXI_REQUIRED;
+                strictFlags &= ~(avifStrictFlags)AVIF_STRICT_PIXI_REQUIRED;
             }
             AVIF_CHECKRES(
                 avifDecoderItemValidateProperties(mainItems[c], avifGetConfigurationPropertyName(codecType[c]), &decoder->diag, strictFlags));
@@ -5807,7 +5807,7 @@ static avifBool avifDecoderDataFrameFullyDecoded(const avifDecoderData * data)
 }
 
 #if defined(AVIF_ENABLE_EXPERIMENTAL_SAMPLE_TRANSFORM)
-avifResult avifDecoderApplySampleTransform(const avifDecoder * decoder, avifImage * dstImage)
+static avifResult avifDecoderApplySampleTransform(const avifDecoder * decoder, avifImage * dstImage)
 {
     if (dstImage->depth != decoder->data->meta->sampleTransformDepth) {
         AVIF_ASSERT_OR_RETURN(dstImage->yuvPlanes[0] != NULL);
diff --git a/src/reformat.c b/src/reformat.c
index a96f67d419..658d5ac8b4 100644
--- a/src/reformat.c
+++ b/src/reformat.c
@@ -1747,10 +1747,10 @@ void avifGetRGBAPixel(const avifRGBImage * src, uint32_t x, uint32_t y, const av
 
     const uint8_t * const srcPixel = &src->pixels[y * src->rowBytes + x * info->pixelBytes];
     if (info->channelBytes > 1) {
-        uint16_t r = *((uint16_t *)(&srcPixel[info->offsetBytesR]));
-        uint16_t g = *((uint16_t *)(&srcPixel[info->offsetBytesG]));
-        uint16_t b = *((uint16_t *)(&srcPixel[info->offsetBytesB]));
-        uint16_t a = avifRGBFormatHasAlpha(src->format) ? *((uint16_t *)(&srcPixel[info->offsetBytesA])) : (uint16_t)info->maxChannel;
+        uint16_t r = *((const uint16_t *)(&srcPixel[info->offsetBytesR]));
+        uint16_t g = *((const uint16_t *)(&srcPixel[info->offsetBytesG]));
+        uint16_t b = *((const uint16_t *)(&srcPixel[info->offsetBytesB]));
+        uint16_t a = avifRGBFormatHasAlpha(src->format) ? *((const uint16_t *)(&srcPixel[info->offsetBytesA])) : (uint16_t)info->maxChannel;
         if (src->isFloat) {
             rgbaPixel[0] = avifF16ToFloat(r);
             rgbaPixel[1] = avifF16ToFloat(g);
diff --git a/src/write.c b/src/write.c
index 9d4fb0a561..2e0519ea9d 100644
--- a/src/write.c
+++ b/src/write.c
@@ -248,7 +248,7 @@ typedef struct avifEncoderData
 static void avifEncoderDataDestroy(avifEncoderData * data);
 
 // Returns NULL if a memory allocation failed.
-static avifEncoderData * avifEncoderDataCreate()
+static avifEncoderData * avifEncoderDataCreate(void)
 {
     avifEncoderData * data = (avifEncoderData *)avifAlloc(sizeof(avifEncoderData));
     if (!data) {
@@ -982,7 +982,7 @@ static avifResult avifEncoderWriteSampleTransformTokens(avifRWStream * s, const
 
         if (token->type == AVIF_SAMPLE_TRANSFORM_CONSTANT) {
             // TODO(yguyon): Verify two's complement representation is guaranteed here.
-            const uint32_t constant = *(uint32_t *)&token->constant;
+            const uint32_t constant = *(const uint32_t *)&token->constant;
             AVIF_CHECKRES(avifRWStreamWriteU32(s, constant)); // signed int(1<<(bit_depth+3)) constant;
         } else if (token->type == AVIF_SAMPLE_TRANSFORM_INPUT_IMAGE_ITEM_INDEX) {
             AVIF_CHECKRES(avifRWStreamWriteU8(s, token->inputImageItemIndex)); // unsigned int(8) input_image_item_index;
@@ -1289,7 +1289,7 @@ static avifResult avifImageApplyImgOpConst(avifImage * result,
     // Postfix notation.
     const avifSampleTransformToken tokens[] = { { AVIF_SAMPLE_TRANSFORM_INPUT_IMAGE_ITEM_INDEX, 0, /*inputImageItemIndex=*/1 },
                                                 { AVIF_SAMPLE_TRANSFORM_CONSTANT, constant, 0 },
-                                                { op, 0, 0 } };
+                                                { (uint8_t)op, 0, 0 } };
     return avifImageApplyOperations(result, AVIF_SAMPLE_TRANSFORM_BIT_DEPTH_32, /*numTokens=*/3, tokens, /*numInputImageItems=*/1, &inputImageItem, planes);
 }