diff --git a/src/asm/fstack.cpp b/src/asm/fstack.cpp
index f928316e..01a026a9 100644
--- a/src/asm/fstack.cpp
+++ b/src/asm/fstack.cpp
@@ -356,11 +356,8 @@ void fstk_RunMacro(char const *macroName, MacroArgs &args) {
 		std::vector<uint32_t> const &srcIters = macro->src->iters();
 
 		for (uint32_t i = srcIters.size(); i--;) {
-			char buf[sizeof("::REPT~4294967295")]; // UINT32_MAX
-
-			if (sprintf(buf, "::REPT~%" PRIu32, srcIters[i]) < 0)
-				fatalerror("Failed to write macro invocation info: %s\n", strerror(errno));
-			fileInfoName.append(buf);
+			fileInfoName.append("::REPT~");
+			fileInfoName.append(std::to_string(srcIters[i]));
 		}
 	}
 	fileInfoName.append("::");
diff --git a/src/link/object.cpp b/src/link/object.cpp
index 01411b0f..4568d065 100644
--- a/src/link/object.cpp
+++ b/src/link/object.cpp
@@ -462,10 +462,9 @@ static void readAssertion(
     uint32_t i,
     std::vector<FileStackNode> const &fileNodes
 ) {
-	char assertName[sizeof("Assertion #4294967295")]; // UINT32_MAX
-
-	snprintf(assertName, sizeof(assertName), "Assertion #%" PRIu32, i);
+	std::string assertName("Assertion #");
 
+	assertName += std::to_string(i);
 	readPatch(file, assert.patch, fileName, assertName, 0, fileNodes);
 	tryReadstring(assert.message, file, "%s: Cannot read assertion's message: %s", fileName);
 }
diff --git a/test/gfx/rgbgfx_test.cpp b/test/gfx/rgbgfx_test.cpp
index b3e58f56..58a40a5c 100644
--- a/test/gfx/rgbgfx_test.cpp
+++ b/test/gfx/rgbgfx_test.cpp
@@ -349,17 +349,13 @@ static char *execProg(char const *name, char * const *argv) {
 		return buf;
 	};
 
-	char cmdLine[32768]; // Max command line size on Windows
-	char *ptr = cmdLine;
+	std::vector<char> cmdLine;
 	for (size_t i = 0; argv[i]; ++i) {
-		char const *src = argv[i];
-		// I miss you, `stpcpy`
-		while (*src) {
-			*ptr++ = *src++;
-		}
-		*ptr++ = ' ';
+		if (i > 0)
+			cmdLine.push_back(' ');
+		cmdLine.insert(cmdLine.end(), argv[i], argv[i] + strlen(argv[i]));
 	}
-	*ptr = '\0';
+	cmdLine.push_back('\0');
 
 	STARTUPINFOA startupInfo;
 	GetStartupInfoA(&startupInfo);
@@ -386,7 +382,16 @@ static char *execProg(char const *name, char * const *argv) {
 
 	PROCESS_INFORMATION child;
 	if (CreateProcessA(
-	        nullptr, cmdLine, nullptr, nullptr, true, 0, nullptr, nullptr, &childStartupInfo, &child
+	        nullptr,
+	        cmdLine.data(),
+	        nullptr,
+	        nullptr,
+	        true,
+	        0,
+	        nullptr,
+	        nullptr,
+	        &childStartupInfo,
+	        &child
 	    )
 	    == 0) {
 		return winStrerror(GetLastError());