diff --git a/engines/sci/engine/guest_additions.cpp b/engines/sci/engine/guest_additions.cpp
index 4a3afcdca92b..6ed2cd901a4f 100644
--- a/engines/sci/engine/guest_additions.cpp
+++ b/engines/sci/engine/guest_additions.cpp
@@ -397,7 +397,7 @@ static const byte SRTorinPatch[] = {
 };
 
 void GuestAdditions::patchGameSaveRestoreTorin(Script &script) const {
-	const uint16 address = script.validateExportFunc(2, true);
+	const uint32 address = script.validateExportFunc(2, true);
 	byte *patchPtr = const_cast<byte *>(script.getBuf(address));
 	memcpy(patchPtr, SRTorinPatch, sizeof(SRTorinPatch));
 	if (g_sci->isBE()) {
diff --git a/engines/sci/engine/kscripts.cpp b/engines/sci/engine/kscripts.cpp
index 30a1fab71a32..98c35fcb497f 100644
--- a/engines/sci/engine/kscripts.cpp
+++ b/engines/sci/engine/kscripts.cpp
@@ -246,7 +246,7 @@ reg_t kScriptID(EngineState *s, int argc, reg_t *argv) {
 		return NULL_REG;
 	}
 
-	uint16 address = scr->validateExportFunc(index, true);
+	uint32 address = scr->validateExportFunc(index, true);
 
 	// Point to the heap for SCI1.1 - SCI2.1 games
 	if (getSciVersion() >= SCI_VERSION_1_1 && getSciVersion() <= SCI_VERSION_2_1_LATE)
diff --git a/engines/sci/engine/script.cpp b/engines/sci/engine/script.cpp
index fa17dc041948..cd75a9796941 100644
--- a/engines/sci/engine/script.cpp
+++ b/engines/sci/engine/script.cpp
@@ -505,6 +505,7 @@ void Script::identifyOffsets() {
 		if (_buf->size() < 22)
 			error("Script::identifyOffsets(): script %d smaller than expected SCI3-header", _nr);
 
+		_codeOffset = _buf->getUint32LEAt(0);
 		sci3StringOffset = _buf->getUint32LEAt(4);
 		sci3RelocationOffset = _buf->getUint32LEAt(8);
 
@@ -796,23 +797,29 @@ uint32 Script::validateExportFunc(int pubfunct, bool relocSci3) {
 	if (exportsAreWide)
 		pubfunct *= 2;
 
-	uint32 offset;
+	int offset;
 
 	if (getSciVersion() != SCI_VERSION_3) {
 		offset = _exports.getUint16SEAt(pubfunct);
 	} else {
-		if (!relocSci3)
-			offset = _exports.getUint16SEAt(pubfunct) + getCodeBlockOffsetSci3();
-		else
-			offset = relocateOffsetSci3(pubfunct * 2 + 22);
+		if (!relocSci3) {
+			offset = _exports.getUint16SEAt(pubfunct) + getCodeBlockOffset();
+		} else {
+			offset = relocateOffsetSci3(pubfunct * sizeof(uint16) + /* header size */ 22);
+			// Some offsets below 0xFFFF are left as-is in the export table,
+			// e.g. Lighthouse script 64990
+			if (offset == -1) {
+				offset = _exports.getUint16SEAt(pubfunct) + getCodeBlockOffset();
+			}
+		}
 	}
 
 	// TODO: Check if this should be done for SCI1.1 games as well
 	if (getSciVersion() >= SCI_VERSION_2 && offset == 0) {
-		offset = _codeOffset;
+		offset = getCodeBlockOffset();
 	}
 
-	if (offset >= _buf->size())
+	if (offset == -1 || offset >= (int)_buf->size())
 		error("Invalid export function pointer");
 
 	return offset;
diff --git a/engines/sci/engine/script.h b/engines/sci/engine/script.h
index 2be3fd026466..f63b31264705 100644
--- a/engines/sci/engine/script.h
+++ b/engines/sci/engine/script.h
@@ -260,9 +260,10 @@ class Script : public SegmentObj {
 	int relocateOffsetSci3(uint32 offset) const;
 
 	/**
-	 * Gets an offset to the beginning of the code block in a SCI3 script
+	 * Gets an offset to the beginning of the code block in a SCI1.1 or later
+	 * script
 	 */
-	int getCodeBlockOffsetSci3() { return _buf->getInt32SEAt(0); }
+	int getCodeBlockOffset() { return _codeOffset; }
 
 	/**
 	 * Get the offset array