diff --git a/src/link/assign.cpp b/src/link/assign.cpp
index 1e3c93bd..b7bd1b5c 100644
--- a/src/link/assign.cpp
+++ b/src/link/assign.cpp
@@ -270,6 +270,7 @@ static void placeSection(Section &section) {
 		assignSection(section, location);
 
 		// Update the free space
+		assume(section.org + section.size <= UINT16_MAX);
 		uint16_t sectionEnd = section.org + section.size;
 		bool noLeftSpace = freeSpace.address == section.org;
 		bool noRightSpace = freeSpace.address + freeSpace.size == sectionEnd;
diff --git a/src/link/output.cpp b/src/link/output.cpp
index 6e273367..8562d0bf 100644
--- a/src/link/output.cpp
+++ b/src/link/output.cpp
@@ -181,6 +181,7 @@ static void
 			}
 
 			// Output the section itself
+			assume(section->size == section->data.size());
 			fwrite(section->data.data(), 1, section->size, outputFile);
 			offset += section->size;
 
@@ -473,6 +474,7 @@ static void writeMapBank(SortedSections const &sectList, SectionType type, uint3
 
 		writeEmptySpace(prevEndAddr, sect.org);
 
+		assume(sect.org + sect.size <= UINT16_MAX);
 		prevEndAddr = sect.org + sect.size;
 
 		fprintf(mapFile, "\tSECTION: $%04" PRIx16, sect.org);