Use `%zu` as format specifier for printing `size_t` for better portability.
--- a/icebram/icebram.cc	2023-12-12 13:01:19.000000000 +0100
+++ b/icebram/icebram.cc	2024-01-10 14:32:01.012119690 +0100
@@ -457,32 +457,32 @@ update(struct app_opts *opts)
 	// Perform checks
 	if ((hf_to.word_size() > 0) && (hf_from.word_size() > hf_to.word_size())) {
 		if (opts->verbose)
-			fprintf(stderr, "Padding to_hexfile words from %lu bits to %lu bits\n",
+			fprintf(stderr, "Padding to_hexfile words from %zu bits to %zu bits\n",
 				hf_to.word_size(), hf_from.word_size());
 		hf_to.pad_words_to(hf_from.word_size());
 	}
 
 	if (hf_to.word_size() != hf_from.word_size()) {
-		fprintf(stderr, "Hexfiles have different word sizes! (%lu bits vs. %lu bits)\n",
+		fprintf(stderr, "Hexfiles have different word sizes! (%zu bits vs. %zu bits)\n",
 			hf_from.word_size(), hf_to.word_size());
 		return 1;
 	}
 
 	if ((hf_to.size() > 0) && (hf_from.size() > hf_to.size())) {
 		if (opts->verbose)
-			fprintf(stderr, "Padding to_hexfile from %lu words to %lu\n",
+			fprintf(stderr, "Padding to_hexfile from %zu words to %zu\n",
 				hf_to.size(), hf_from.size());
 		hf_to.pad_to(hf_from.size());
 	}
 
 	if (hf_to.size() != hf_from.size()) {
-		fprintf(stderr, "Hexfiles have different number of words! (%lu vs. %lu)\n",
+		fprintf(stderr, "Hexfiles have different number of words! (%zu vs. %zu)\n",
 			hf_from.size(), hf_to.size());
 		return 1;
 	}
 
 	if (hf_from.size() % 256 != 0) {
-		fprintf(stderr, "Hexfile number of words (%lu) is not divisible by 256!\n",
+		fprintf(stderr, "Hexfile number of words (%zu) is not divisible by 256!\n",
 			hf_from.size());
 		return 1;
 	}
@@ -494,20 +494,20 @@ update(struct app_opts *opts)
 
 	// Debug
 	if (opts->verbose)
-		fprintf(stderr, "Loaded pattern for %lu bits wide and %lu words deep memory.\n",
+		fprintf(stderr, "Loaded pattern for %zu bits wide and %zu words deep memory.\n",
 			hf_from.word_size(), hf_from.size());
 
 	// Generate mapping for slices
 	std::map<std::vector<bool>, std::pair<std::vector<bool>, int>> pattern = hf_from.generate_pattern(hf_to);
 	if (opts->verbose)
-		fprintf(stderr, "Extracted %lu bit slices from from/to hexfile data.\n", pattern.size());
+		fprintf(stderr, "Extracted %zu bit slices from from/to hexfile data.\n", pattern.size());
 
 	// Load FPGA config from stdin
 	AscFile bitstream;
 	bitstream.load_config(std::cin);
 
 	if (opts->verbose)
-		fprintf(stderr, "Found %lu initialized bram cells in asc file.\n", bitstream.n_ebrs());
+		fprintf(stderr, "Found %zu initialized bram cells in asc file.\n", bitstream.n_ebrs());
 
 	// Apply pattern
 	bitstream.apply_pattern(pattern);
diff --color -rupN a/icepack/icepack.cc b/icepack/icepack.cc
--- a/icepack/icepack.cc	2023-12-12 13:01:19.000000000 +0100
+++ b/icepack/icepack.cc	2024-01-10 14:30:17.829617241 +0100
@@ -902,10 +902,10 @@ void FpgaConfig::write_ascii(std::ostrea
 				cic.get_cram_index(bit_x, bit_y, cram_bank, cram_x, cram_y);
 				tile_bits.insert(tile_bit_t(cram_bank, cram_x, cram_y));
 				if (cram_x > int(this->cram[cram_bank].size())) {
-					error("cram_x %d (bit %d, %d) larger than bank size %lu\n", cram_x, bit_x, bit_y, this->cram[cram_bank].size());
+					error("cram_x %d (bit %d, %d) larger than bank size %zu\n", cram_x, bit_x, bit_y, this->cram[cram_bank].size());
 				}
 				if (cram_y > int(this->cram[cram_bank][cram_x].size())) {
-					error("cram_y %d (bit %d, %d) larger than bank %d size %lu\n", cram_y, bit_x, bit_y, cram_bank, this->cram[cram_bank][cram_x].size());
+					error("cram_y %d (bit %d, %d) larger than bank %d size %zu\n", cram_y, bit_x, bit_y, cram_bank, this->cram[cram_bank][cram_x].size());
 				}
 				ofs << (this->cram[cram_bank][cram_x][cram_y] ? '1' : '0');
 			}
@@ -924,11 +924,11 @@ void FpgaConfig::write_ascii(std::ostrea
 						int bram_bank, bram_x, bram_y;
 						bic.get_bram_index(bit_x+i, bit_y, bram_bank, bram_x, bram_y);
 						if (bram_x >= int(this->bram[bram_bank].size())) {
-							error("%d %d bram_x %d higher than loaded bram size %lu\n",bit_x+i, bit_y, bram_x,  this->bram[bram_bank].size());
+							error("%d %d bram_x %d higher than loaded bram size %zu\n",bit_x+i, bit_y, bram_x,  this->bram[bram_bank].size());
 							break;
 						}
 						if (bram_y >= int(this->bram[bram_bank][bram_x].size())) {
-							error("bram_y %d higher than loaded bram size %lu\n", bram_y,  this->bram[bram_bank][bram_x].size());
+							error("bram_y %d higher than loaded bram size %zu\n", bram_y,  this->bram[bram_bank][bram_x].size());
 							break;
 						}
 						if (this->bram[bram_bank][bram_x][bram_y])