diff --git a/src/error_gui.cpp b/src/error_gui.cpp
index 1d7107bec4..e73da56fdd 100644
--- a/src/error_gui.cpp
+++ b/src/error_gui.cpp
@@ -131,6 +131,12 @@ ErrorMessageData::ErrorMessageData(StringID summary_msg, StringID detailed_msg,
  */
 void ErrorMessageData::CopyOutDParams()
 {
+	if (this->detailed_msg == STR_ERROR_OWNED_BY) {
+		/* The parameters are set by SetDParamsForOwnedBy. */
+		CompanyID company = (CompanyID)GetDParam(OWNED_BY_OWNER_IN_PARAMETERS_OFFSET);
+		if (company < MAX_COMPANIES) face = company;
+	}
+
 	/* Reset parameters */
 	for (size_t i = 0; i < lengthof(this->strings); i++) free(this->strings[i]);
 	memset(this->decode_params, 0, sizeof(this->decode_params));
@@ -140,11 +146,6 @@ void ErrorMessageData::CopyOutDParams()
 	if (this->textref_stack_size > 0) StartTextRefStackUsage(this->textref_stack_grffile, this->textref_stack_size, this->textref_stack);
 	CopyOutDParam(this->decode_params, this->strings, this->detailed_msg == INVALID_STRING_ID ? this->summary_msg : this->detailed_msg, lengthof(this->decode_params));
 	if (this->textref_stack_size > 0) StopTextRefStackUsage();
-
-	if (this->detailed_msg == STR_ERROR_OWNED_BY) {
-		CompanyID company = (CompanyID)GetDParamX(this->decode_params, OWNED_BY_OWNER_IN_PARAMETERS_OFFSET);
-		if (company < MAX_COMPANIES) face = company;
-	}
 }
 
 /**
diff --git a/src/strings_func.h b/src/strings_func.h
index cc63efdb98..ec3f82cd3f 100644
--- a/src/strings_func.h
+++ b/src/strings_func.h
@@ -211,17 +211,6 @@ void CopyInDParam(const uint64 *src, int num);
 void CopyOutDParam(uint64 *dst, int num);
 void CopyOutDParam(uint64 *dst, const char **strings, StringID string, int num);
 
-/**
- * Get the current string parameter at index \a n from parameter array \a s.
- * @param s Array of string parameters.
- * @param n Index of the string parameter.
- * @return Value of the requested string parameter.
- */
-static inline uint64 GetDParamX(const uint64 *s, uint n)
-{
-	return s[n];
-}
-
 /**
  * Get the current string parameter at index \a n from the global string parameter array.
  * @param n Index of the string parameter.