diff --git a/src/asm/parser.y b/src/asm/parser.y
index 89d6164a..41549b60 100644
--- a/src/asm/parser.y
+++ b/src/asm/parser.y
@@ -1945,7 +1945,7 @@ z80_ldio	: T_Z80_LDH T_MODE_A T_COMMA op_mem_ind {
 
 c_ind		: T_LBRACK T_MODE_C T_RBRACK
 		| T_LBRACK relocexpr T_OP_ADD T_MODE_C T_RBRACK {
-			if (!rpn_isKnown(&$2) || $2.val != 0xff00)
+			if (!rpn_isKnown(&$2) || $2.val != 0xFF00)
 				error("Expected constant expression equal to $FF00 for \"$ff00+c\"\n");
 		}
 ;
diff --git a/src/asm/section.c b/src/asm/section.c
index 6377ad2d..a8acca79 100644
--- a/src/asm/section.c
+++ b/src/asm/section.c
@@ -161,7 +161,7 @@ static unsigned int mergeSectUnion(struct Section *sect, enum SectionType type,
 			   != (sect->alignOfs & mask(alignment))) {
 			fail("Section already declared with incompatible %u"
 			     "-byte alignment (offset %" PRIu16 ")\n",
-			     1u << sect->align, sect->alignOfs);
+			     1U << sect->align, sect->alignOfs);
 		} else if (alignment > sect->align) {
 			// If the section is not fixed, its alignment is the largest of both
 			sect->align = alignment;
@@ -212,7 +212,7 @@ static unsigned int mergeFragments(struct Section *sect, enum SectionType type,
 		} else if ((curOfs & mask(sect->align)) != (sect->alignOfs & mask(alignment))) {
 			fail("Section already declared with incompatible %u"
 			     "-byte alignment (offset %" PRIu16 ")\n",
-			     1u << sect->align, sect->alignOfs);
+			     1U << sect->align, sect->alignOfs);
 		} else if (alignment > sect->align) {
 			// If the section is not fixed, its alignment is the largest of both
 			sect->align = alignment;
diff --git a/src/extern/getopt.c b/src/extern/getopt.c
index 08c8b08d..652893f2 100644
--- a/src/extern/getopt.c
+++ b/src/extern/getopt.c
@@ -82,7 +82,7 @@ static int getopt(int argc, char *argv[], char const *optstring)
 	k = mbtowc(&c, argv[musl_optind] + musl_optpos, MB_LEN_MAX);
 	if (k < 0) {
 		k = 1;
-		c = 0xfffd; /* replacement char */
+		c = 0xFFFD; /* replacement char */
 	}
 	optchar = argv[musl_optind] + musl_optpos;
 	musl_optpos += k;
diff --git a/src/extern/utf8decoder.c b/src/extern/utf8decoder.c
index f15a1002..7bc95f2a 100644
--- a/src/extern/utf8decoder.c
+++ b/src/extern/utf8decoder.c
@@ -43,8 +43,8 @@ uint32_t decode(uint32_t *state, uint32_t *codep, uint8_t byte)
 	uint32_t type = utf8d[byte];
 
 	*codep = (*state != 0) ?
-			(byte & 0x3fu) | (*codep << 6) :
-			(0xff >> type) & (byte);
+			(byte & 0x3FU) | (*codep << 6) :
+			(0xFF >> type) & (byte);
 
 	*state = utf8d[256 + *state * 16 + type];
 	return *state;
diff --git a/src/gfx/reverse.cpp b/src/gfx/reverse.cpp
index 9003706a..969877a0 100644
--- a/src/gfx/reverse.cpp
+++ b/src/gfx/reverse.cpp
@@ -144,7 +144,7 @@ void reverse() {
 	// TODO: -U
 
 	std::vector<std::array<Rgba, 4>> palettes{
-	    {Rgba(0xffffffff), Rgba(0xaaaaaaff), Rgba(0x555555ff), Rgba(0x000000ff)}
+	    {Rgba(0xFFFFFFFF), Rgba(0xAAAAAAFF), Rgba(0x555555FF), Rgba(0x000000FF)}
     };
 	if (!options.palettes.empty()) {
 		File file;
diff --git a/src/hashmap.c b/src/hashmap.c
index c6ce7b6a..55b8592f 100644
--- a/src/hashmap.c
+++ b/src/hashmap.c
@@ -29,7 +29,7 @@ struct HashMapEntry {
 	struct HashMapEntry *next;
 };
 
-#define FNV_OFFSET_BASIS 0x811c9dc5
+#define FNV_OFFSET_BASIS 0x811C9DC5
 #define FNV_PRIME 16777619
 
 // FNV-1a hash
diff --git a/test/gfx/randtilegen.c b/test/gfx/randtilegen.c
index 639ace57..bc83f995 100644
--- a/test/gfx/randtilegen.c
+++ b/test/gfx/randtilegen.c
@@ -53,7 +53,7 @@ static unsigned long long getRandomBits(unsigned count) {
 		randbits |= (unsigned long long)data << randcount;
 		randcount += 8;
 	}
-	unsigned long long result = randbits & ((1ull << count) - 1);
+	unsigned long long result = randbits & ((1ULL << count) - 1);
 	randbits >>= count;
 	randcount -= count;
 	return result;