diff --git a/Makefile b/Makefile
index 6b66bd640..a6f4235d7 100644
--- a/Makefile
+++ b/Makefile
@@ -176,7 +176,7 @@ ifeq ($(OS), Haiku)
 CXXFLAGS += -D_DEFAULT_SOURCE
 endif
 
-YOSYS_VER := 0.52+117
+YOSYS_VER := 0.52+137
 YOSYS_MAJOR := $(shell echo $(YOSYS_VER) | cut -d'.' -f1)
 YOSYS_MINOR := $(shell echo $(YOSYS_VER) | cut -d'.' -f2)
 YOSYS_COMMIT := $(shell echo $(YOSYS_VER) | cut -d'.' -f3)
@@ -847,7 +847,7 @@ $(PROGRAM_PREFIX)yosys-config: misc/yosys-config.in $(YOSYS_SRC)/Makefile
 .PHONY: check-git-abc
 
 check-git-abc:
-	@if [ ! -d "$(YOSYS_SRC)/abc" ]; then \
+	@if [ ! -d "$(YOSYS_SRC)/abc" ] && git -C "$(YOSYS_SRC)" status >/dev/null 2>&1; then \
 		echo "Error: The 'abc' directory does not exist."; \
 		echo "Initialize the submodule: Run 'git submodule update --init' to set up 'abc' as a submodule."; \
 		exit 1; \
@@ -873,6 +873,12 @@ check-git-abc:
 		echo "3. Initialize the submodule: Run 'git submodule update --init' to set up 'abc' as a submodule."; \
 		echo "4. Reapply your changes: Move your saved changes back to the 'abc' directory, if necessary."; \
 		exit 1; \
+	elif ! git -C "$(YOSYS_SRC)" status >/dev/null 2>&1; then \
+		echo "$(realpath $(YOSYS_SRC)) is not configured as a git repository, and 'abc' folder is missing."; \
+		echo "If you already have ABC, set 'ABCEXTERNAL' make variable to point to ABC executable."; \
+		echo "Otherwise, download release archive 'yosys.tar.gz' from https://github.com/YosysHQ/yosys/releases."; \
+		echo "    ('Source code' archive does not contain submodules.)"; \
+		exit 1; \
 	else \
 		echo "Initialize the submodule: Run 'git submodule update --init' to set up 'abc' as a submodule."; \
 		exit 1; \
diff --git a/kernel/gzip.cc b/kernel/gzip.cc
index d44b03517..4567fe03b 100644
--- a/kernel/gzip.cc
+++ b/kernel/gzip.cc
@@ -100,11 +100,12 @@ gzip_istream::ibuf::~ibuf() {
 
 // Takes a successfully opened ifstream. If it's gzipped, returns an istream. Otherwise,
 // returns the original ifstream, rewound to the start.
+// Never returns nullptr or failed state istream*
 std::istream* uncompressed(const std::string filename, std::ios_base::openmode mode) {
 	std::ifstream* f = new std::ifstream();
 	f->open(filename, mode);
 	if (f->fail())
-		return f;
+		log_cmd_error("Can't open input file `%s' for reading: %s\n", filename.c_str(), strerror(errno));
 	// Check for gzip magic
 	unsigned char magic[3];
 	int n = 0;
@@ -124,7 +125,7 @@ std::istream* uncompressed(const std::string filename, std::ios_base::openmode m
 				filename.c_str(), unsigned(magic[2]));
 		gzip_istream* s = new gzip_istream();
 		delete f;
-		s->open(filename.c_str());
+		log_assert(s->open(filename.c_str()));
 		return s;
 #else
 		log_cmd_error("File `%s' is a gzip file, but Yosys is compiled without zlib.\n", filename.c_str());
diff --git a/kernel/register.cc b/kernel/register.cc
index c52bfb5b8..a82f93555 100644
--- a/kernel/register.cc
+++ b/kernel/register.cc
@@ -472,8 +472,6 @@ void Frontend::extra_args(std::istream *&f, std::string &filename, std::vector<s
 			yosys_input_files.insert(filename);
 			f = uncompressed(filename, bin_input ? std::ifstream::binary : std::ifstream::in);
 		}
-		if (f == NULL)
-			log_cmd_error("Can't open input file `%s' for reading: %s\n", filename.c_str(), strerror(errno));
 
 		for (size_t i = argidx+1; i < args.size(); i++)
 			if (args[i].compare(0, 1, "-") == 0)
diff --git a/passes/cmds/stat.cc b/passes/cmds/stat.cc
index b76a8d11e..b7cc27847 100644
--- a/passes/cmds/stat.cc
+++ b/passes/cmds/stat.cc
@@ -349,8 +349,6 @@ void read_liberty_cellarea(dict<IdString, cell_area_t> &cell_area, string libert
 {
 	std::istream* f = uncompressed(liberty_file.c_str());
 	yosys_input_files.insert(liberty_file);
-	if (f->fail())
-		log_cmd_error("Can't open liberty file `%s': %s\n", liberty_file.c_str(), strerror(errno));
 	LibertyParser libparser(*f, liberty_file);
 	delete f;
 
diff --git a/passes/cmds/tee.cc b/passes/cmds/tee.cc
index 39ed4a7a8..853f1bad3 100644
--- a/passes/cmds/tee.cc
+++ b/passes/cmds/tee.cc
@@ -72,7 +72,9 @@ struct TeePass : public Pass {
 			}
 			if ((args[argidx] == "-o" || args[argidx] == "-a") && argidx+1 < args.size()) {
 				const char *open_mode = args[argidx] == "-o" ? "w" : "a+";
-				FILE *f = fopen(args[++argidx].c_str(), open_mode);
+				auto path = args[++argidx];
+				rewrite_filename(path);
+				FILE *f = fopen(path.c_str(), open_mode);
 				yosys_input_files.insert(args[argidx]);
 				if (f == NULL) {
 					for (auto cf : files_to_close)
diff --git a/passes/techmap/clockgate.cc b/passes/techmap/clockgate.cc
index 2305cfc94..508e66d23 100644
--- a/passes/techmap/clockgate.cc
+++ b/passes/techmap/clockgate.cc
@@ -310,8 +310,6 @@ struct ClockgatePass : public Pass {
 			LibertyMergedCells merged;
 			for (auto path : liberty_files) {
 				std::istream* f = uncompressed(path);
-				if (f->fail())
-					log_cmd_error("Can't open liberty file `%s': %s\n", path.c_str(), strerror(errno));
 				LibertyParser p(*f, path);
 				merged.merge(p);
 				delete f;
diff --git a/passes/techmap/dfflibmap.cc b/passes/techmap/dfflibmap.cc
index ae13a6ddd..d00fee83b 100644
--- a/passes/techmap/dfflibmap.cc
+++ b/passes/techmap/dfflibmap.cc
@@ -635,8 +635,6 @@ struct DfflibmapPass : public Pass {
 		LibertyMergedCells merged;
 		for (auto path : liberty_files) {
 			std::istream* f = uncompressed(path);
-			if (f->fail())
-				log_cmd_error("Can't open liberty file `%s': %s\n", path.c_str(), strerror(errno));
 			LibertyParser p(*f, path);
 			merged.merge(p);
 			delete f;